Text::CSV_XS - phpMan

Command: man perldoc info search(apropos)  


CSV_XS(3pm)                    User Contributed Perl Documentation                    CSV_XS(3pm)

NAME
       Text::CSV_XS - comma-separated values manipulation routines

SYNOPSIS
        # Functional interface
        use Text::CSV_XS qw( csv );

        # Read whole file in memory
        my $aoa = csv (in => "data.csv");    # as array of array
        my $aoh = csv (in => "data.csv",
                       headers => "auto");   # as array of hash

        # Write array of arrays as csv file
        csv (in => $aoa, out => "file.csv", sep_char=> ";");

        # Only show lines where "code" is odd
        csv (in => "data.csv", filter => { code => sub { $_ % 2 }});

        # Object interface
        use Text::CSV_XS;

        my @rows;
        # Read/parse CSV
        my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
        open my $fh, "<:encoding(utf8)", "test.csv" or die "test.csv: $!";
        while (my $row = $csv->getline ($fh)) {
            $row->[2] =~ m/pattern/ or next; # 3rd field should match
            push @rows, $row;
            }
        close $fh;

        # and write as CSV
        open $fh, ">:encoding(utf8)", "new.csv" or die "new.csv: $!";
        $csv->say ($fh, $_) for @rows;
        close $fh or die "new.csv: $!";

DESCRIPTION
       Text::CSV_XS  provides facilities for the composition  and decomposition of comma-
       separated values.  An instance of the Text::CSV_XS class will combine fields into a "CSV"
       string and parse a "CSV" string into fields.

       The module accepts either strings or files as input  and support the use of user-specified
       characters for delimiters, separators, and escapes.

   Embedded newlines
       Important Note:  The default behavior is to accept only ASCII characters in the range from
       0x20 (space) to 0x7E (tilde).   This means that the fields can not contain newlines. If
       your data contains newlines embedded in fields, or characters above 0x7E (tilde), or
       binary data, you must set "binary => 1" in the call to "new". To cover the widest range of
       parsing options, you will always want to set binary.

       But you still have the problem  that you have to pass a correct line to the "parse"
       method, which is more complicated from the usual point of usage:

        my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
        while (<>) {           #  WRONG!
            $csv->parse ($_);
            my @fields = $csv->fields ();
            }

       this will break, as the "while" might read broken lines:  it does not care about the
       quoting. If you need to support embedded newlines,  the way to go is to  not  pass "eol"
       in the parser  (it accepts "\n", "\r", and "\r\n" by default) and then

        my $csv = Text::CSV_XS->new ({ binary => 1 });
        open my $fh, "<", $file or die "$file: $!";
        while (my $row = $csv->getline ($fh)) {
            my @fields = @$row;
            }

       The old(er) way of using global file handles is still supported

        while (my $row = $csv->getline (*ARGV)) { ... }

   Unicode
       Unicode is only tested to work with perl-5.8.2 and up.

       See also "BOM".

       The simplest way to ensure the correct encoding is used for  in- and output is by either
       setting layers on the filehandles, or setting the "encoding" argument for "csv".

        open my $fh, "<:encoding(UTF-8)", "in.csv"  or die "in.csv: $!";
       or
        my $aoa = csv (in => "in.csv",     encoding => "UTF-8");

        open my $fh, ">:encoding(UTF-8)", "out.csv" or die "out.csv: $!";
       or
        csv (in => $aoa, out => "out.csv", encoding => "UTF-8");

       On parsing (both for  "getline" and  "parse"),  if the source is marked being UTF8, then
       all fields that are marked binary will also be marked UTF8.

       On combining ("print"  and  "combine"):  if any of the combining fields was marked UTF8,
       the resulting string will be marked as UTF8.  Note however that all fields  before  the
       first field marked UTF8 and contained 8-bit characters that were not upgraded to UTF8,
       these will be  "bytes"  in the resulting string too, possibly causing unexpected errors.
       If you pass data of different encoding,  or you don't know if there is  different
       encoding, force it to be upgraded before you pass them on:

        $csv->print ($fh, [ map { utf8::upgrade (my $x = $_); $x } @data ]);

       For complete control over encoding, please use Text::CSV::Encoded:

        use Text::CSV::Encoded;
        my $csv = Text::CSV::Encoded->new ({
            encoding_in  => "iso-8859-1", # the encoding comes into   Perl
            encoding_out => "cp1252",     # the encoding comes out of Perl
            });

        $csv = Text::CSV::Encoded->new ({ encoding  => "utf8" });
        # combine () and print () accept *literally* utf8 encoded data
        # parse () and getline () return *literally* utf8 encoded data

        $csv = Text::CSV::Encoded->new ({ encoding  => undef }); # default
        # combine () and print () accept UTF8 marked data
        # parse () and getline () return UTF8 marked data

   BOM
       BOM  (or Byte Order Mark)  handling is available only inside the "header" method.   This
       method supports the following encodings: "utf-8", "utf-1", "utf-32be", "utf-32le",
       "utf-16be", "utf-16le", "utf-ebcdic", "scsu", "bocu-1", and "gb-18030". See Wikipedia
       <https://en.wikipedia.org/wiki/Byte_order_mark>.

       If a file has a BOM, the easiest way to deal with that is

        my $aoh = csv (in => $file, detect_bom => 1);

       All records will be encoded based on the detected BOM.

       This implies a call to the  "header"  method,  which defaults to also set the
       "column_names". So this is not the same as

        my $aoh = csv (in => $file, headers => "auto");

       which only reads the first record to set  "column_names"  but ignores any meaning of
       possible present BOM.

SPECIFICATION
       While no formal specification for CSV exists, RFC 4180
       <https://datatracker.ietf.org/doc/html/rfc4180> (1) describes the common format and
       establishes  "text/csv" as the MIME type registered with the IANA. RFC 7111
       <https://datatracker.ietf.org/doc/html/rfc7111> (2) adds fragments to CSV.

       Many informal documents exist that describe the "CSV" format.   "How To: The Comma
       Separated Value (CSV) File Format" <http://creativyst.com/Doc/Articles/CSV/CSV01.shtml>
       (3)  provides an overview of the  "CSV"  format in the most widely used applications and
       explains how it can best be used and supported.

        1) https://datatracker.ietf.org/doc/html/rfc4180
        2) https://datatracker.ietf.org/doc/html/rfc7111
        3) http://creativyst.com/Doc/Articles/CSV/CSV01.shtml

       The basic rules are as follows:

       CSV  is a delimited data format that has fields/columns separated by the comma character
       and records/rows separated by newlines. Fields that contain a special character (comma,
       newline, or double quote),  must be enclosed in double quotes. However, if a line contains
       a single entry that is the empty string, it may be enclosed in double quotes.  If a
       field's value contains a double quote character it is escaped by placing another double
       quote character next to it. The "CSV" file format does not require a specific character
       encoding, byte order, or line terminator format.

       o Each record is a single line ended by a line feed  (ASCII/"LF"=0x0A) or a carriage
         return and line feed pair (ASCII/"CRLF"="0x0D 0x0A"), however, line-breaks may be
         embedded.

       o Fields are separated by commas.

       o Allowable characters within a "CSV" field include 0x09 ("TAB") and the inclusive range
         of 0x20 (space) through 0x7E (tilde).  In binary mode all characters are accepted, at
         least in quoted fields.

       o A field within  "CSV"  must be surrounded by  double-quotes to  contain  a separator
         character (comma).

       Though this is the most clear and restrictive definition,  Text::CSV_XS  is way more
       liberal than this, and allows extension:

       o Line termination by a single carriage return is accepted by default

       o The separation-, escape-, and escape- characters can be any ASCII character in the range
         from  0x20 (space) to  0x7E (tilde).  Characters outside this range may or may not work
         as expected.  Multibyte characters, like UTF "U+060C" (ARABIC COMMA),   "U+FF0C"
         (FULLWIDTH COMMA),  "U+241B" (SYMBOL FOR ESCAPE), "U+2424" (SYMBOL FOR NEWLINE),
         "U+FF02" (FULLWIDTH QUOTATION MARK), and "U+201C" (LEFT DOUBLE QUOTATION MARK) (to give
         some examples of what might look promising) work for newer versions of perl for
         "sep_char", and "quote_char" but not for "escape_char".

         If you use perl-5.8.2 or higher these three attributes are utf8-decoded, to increase the
         likelihood of success. This way "U+00FE" will be allowed as a quote character.

       o A field in  "CSV"  must be surrounded by double-quotes to make an embedded double-quote,
         represented by a pair of consecutive double-quotes, valid. In binary mode you may
         additionally use the sequence  ""0" for representation of a NULL byte. Using 0x00 in
         binary mode is just as valid.

       o Several violations of the above specification may be lifted by passing some options as
         attributes to the object constructor.

METHODS
   version
       (Class method) Returns the current module version.

   new
       (Class method) Returns a new instance of class Text::CSV_XS. The attributes are described
       by the (optional) hash ref "\%attr".

        my $csv = Text::CSV_XS->new ({ attributes ... });

       The following attributes are available:

       eol

        my $csv = Text::CSV_XS->new ({ eol => $/ });
                  $csv->eol (undef);
        my $eol = $csv->eol;

       The end-of-line string to add to rows for "print" or the record separator for "getline".

       When not passed in a parser instance,  the default behavior is to accept "\n", "\r", and
       "\r\n", so it is probably safer to not specify "eol" at all. Passing "undef" or the empty
       string behave the same.

       When not passed in a generating instance,  records are not terminated at all, so it is
       probably wise to pass something you expect. A safe choice for "eol" on output is either $/
       or "\r\n".

       Common values for "eol" are "\012" ("\n" or Line Feed),  "\015\012" ("\r\n" or Carriage
       Return, Line Feed),  and "\015"  ("\r" or Carriage Return). The "eol" attribute cannot
       exceed 7 (ASCII) characters.

       If both $/ and "eol" equal "\015", parsing lines that end on only a Carriage Return
       without Line Feed, will be "parse"d correct.

       sep_char

        my $csv = Text::CSV_XS->new ({ sep_char => ";" });
                $csv->sep_char (";");
        my $c = $csv->sep_char;

       The char used to separate fields, by default a comma. (",").  Limited to a single-byte
       character, usually in the range from 0x20 (space) to 0x7E (tilde). When longer sequences
       are required, use "sep".

       The separation character can not be equal to the quote character  or to the escape
       character.

       See also "CAVEATS"

       sep

        my $csv = Text::CSV_XS->new ({ sep => "\N{FULLWIDTH COMMA}" });
                  $csv->sep (";");
        my $sep = $csv->sep;

       The chars used to separate fields, by default undefined. Limited to 8 bytes.

       When set, overrules "sep_char".  If its length is one byte it acts as an alias to
       "sep_char".

       See also "CAVEATS"

       quote_char

        my $csv = Text::CSV_XS->new ({ quote_char => "'" });
                $csv->quote_char (undef);
        my $c = $csv->quote_char;

       The character to quote fields containing blanks or binary data,  by default the double
       quote character (""").  A value of undef suppresses quote chars (for simple cases only).
       Limited to a single-byte character, usually in the range from  0x20 (space) to  0x7E
       (tilde).  When longer sequences are required, use "quote".

       "quote_char" can not be equal to "sep_char".

       quote

        my $csv = Text::CSV_XS->new ({ quote => "\N{FULLWIDTH QUOTATION MARK}" });
                    $csv->quote ("'");
        my $quote = $csv->quote;

       The chars used to quote fields, by default undefined. Limited to 8 bytes.

       When set, overrules "quote_char". If its length is one byte it acts as an alias to
       "quote_char".

       This method does not support "undef".  Use "quote_char" to disable quotation.

       See also "CAVEATS"

       escape_char

        my $csv = Text::CSV_XS->new ({ escape_char => "\\" });
                $csv->escape_char (":");
        my $c = $csv->escape_char;

       The character to  escape  certain characters inside quoted fields.  This is limited to a
       single-byte  character,  usually  in the  range from  0x20 (space) to 0x7E (tilde).

       The "escape_char" defaults to being the double-quote mark ("""). In other words the same
       as the default "quote_char". This means that doubling the quote mark in a field escapes
       it:

        "foo","bar","Escape ""quote mark"" with two ""quote marks""","baz"

       If  you  change  the   "quote_char"  without  changing  the "escape_char",  the
       "escape_char" will still be the double-quote (""").  If instead you want to escape the
       "quote_char" by doubling it you will need to also change the  "escape_char"  to be the
       same as what you have changed the "quote_char" to.

       Setting "escape_char" to <undef> or "" will disable escaping completely and is greatly
       discouraged. This will also disable "escape_null".

       The escape character can not be equal to the separation character.

       binary

        my $csv = Text::CSV_XS->new ({ binary => 1 });
                $csv->binary (0);
        my $f = $csv->binary;

       If this attribute is 1,  you may use binary characters in quoted fields, including line
       feeds, carriage returns and "NULL" bytes. (The latter could be escaped as ""0".) By
       default this feature is off.

       If a string is marked UTF8,  "binary" will be turned on automatically when binary
       characters other than "CR" and "NL" are encountered.   Note that a simple string like
       "\x{00a0}" might still be binary, but not marked UTF8, so setting "{ binary => 1 }" is
       still a wise option.

       strict

        my $csv = Text::CSV_XS->new ({ strict => 1 });
                $csv->strict (0);
        my $f = $csv->strict;

       If this attribute is set to 1, any row that parses to a different number of fields than
       the previous row will cause the parser to throw error 2014.

       skip_empty_rows

        my $csv = Text::CSV_XS->new ({ skip_empty_rows => 1 });
                $csv->skip_empty_rows (0);
        my $f = $csv->skip_empty_rows;

       If this attribute is set to 1,  any row that has an  "eol" immediately following the start
       of line will be skipped.  Default behavior is to return one single empty field.

       This attribute is only used in parsing.

       formula_handling

       formula

        my $csv = Text::CSV_XS->new ({ formula => "none" });
                $csv->formula ("none");
        my $f = $csv->formula;

       This defines the behavior of fields containing formulas. As formulas are considered
       dangerous in spreadsheets, this attribute can define an optional action to be taken if a
       field starts with an equal sign ("=").

       For purpose of code-readability, this can also be written as

        my $csv = Text::CSV_XS->new ({ formula_handling => "none" });
                $csv->formula_handling ("none");
        my $f = $csv->formula_handling;

       Possible values for this attribute are

       none
         Take no specific action. This is the default.

          $csv->formula ("none");

       die
         Cause the process to "die" whenever a leading "=" is encountered.

          $csv->formula ("die");

       croak
         Cause the process to "croak" whenever a leading "=" is encountered.  (See Carp)

          $csv->formula ("croak");

       diag
         Report position and content of the field whenever a leading  "=" is found.  The value of
         the field is unchanged.

          $csv->formula ("diag");

       empty
         Replace the content of fields that start with a "=" with the empty string.

          $csv->formula ("empty");
          $csv->formula ("");

       undef
         Replace the content of fields that start with a "=" with "undef".

          $csv->formula ("undef");
          $csv->formula (undef);

       a callback
         Modify the content of fields that start with a  "="  with the return-value of the
         callback.  The original content of the field is available inside the callback as $_;

          # Replace all formula's with 42
          $csv->formula (sub { 42; });

          # same as $csv->formula ("empty") but slower
          $csv->formula (sub { "" });

          # Allow =4+12
          $csv->formula (sub { s/^=(\d+\+\d+)$/$1/eer });

          # Allow more complex calculations
          $csv->formula (sub { eval { s{^=([-+*/0-9()]+)$}{$1}ee }; $_ });

       All other values will give a warning and then fallback to "diag".

       decode_utf8

        my $csv = Text::CSV_XS->new ({ decode_utf8 => 1 });
                $csv->decode_utf8 (0);
        my $f = $csv->decode_utf8;

       This attributes defaults to TRUE.

       While parsing,  fields that are valid UTF-8, are automatically set to be UTF-8, so that

         $csv->parse ("\xC4\xA8\n");

       results in

         PV("\304\250"\0) [UTF8 "\x{128}"]

       Sometimes it might not be a desired action.  To prevent those upgrades, set this attribute
       to false, and the result will be

         PV("\304\250"\0)

       auto_diag

        my $csv = Text::CSV_XS->new ({ auto_diag => 1 });
                $csv->auto_diag (2);
        my $l = $csv->auto_diag;

       Set this attribute to a number between 1 and 9 causes  "error_diag" to be automatically
       called in void context upon errors.

       In case of error "2012 - EOF", this call will be void.

       If "auto_diag" is set to a numeric value greater than 1, it will "die" on errors instead
       of "warn".  If set to anything unrecognized,  it will be silently ignored.

       Future extensions to this feature will include more reliable auto-detection of  "autodie"
       being active in the scope of which the error occurred which will increment the value of
       "auto_diag" with  1 the moment the error is detected.

       diag_verbose

        my $csv = Text::CSV_XS->new ({ diag_verbose => 1 });
                $csv->diag_verbose (2);
        my $l = $csv->diag_verbose;

       Set the verbosity of the output triggered by "auto_diag".   Currently only adds the
       current  input-record-number  (if known)  to the diagnostic output with an indication of
       the position of the error.

       blank_is_undef

        my $csv = Text::CSV_XS->new ({ blank_is_undef => 1 });
                $csv->blank_is_undef (0);
        my $f = $csv->blank_is_undef;

       Under normal circumstances, "CSV" data makes no distinction between quoted- and unquoted
       empty fields.  These both end up in an empty string field once read, thus

        1,"",," ",2

       is read as

        ("1", "", "", " ", "2")

       When writing  "CSV" files with either  "always_quote" or  "quote_empty" set, the unquoted
       empty field is the result of an undefined value.   To enable this distinction when
       reading "CSV"  data,  the  "blank_is_undef"  attribute will cause  unquoted empty fields
       to be set to "undef", causing the above to be parsed as

        ("1", "", undef, " ", "2")

       Note that this is specifically important when loading  "CSV" fields into a database that
       allows "NULL" values,  as the perl equivalent for "NULL" is "undef" in DBI land.

       empty_is_undef

        my $csv = Text::CSV_XS->new ({ empty_is_undef => 1 });
                $csv->empty_is_undef (0);
        my $f = $csv->empty_is_undef;

       Going one  step  further  than  "blank_is_undef",  this attribute converts all empty
       fields to "undef", so

        1,"",," ",2

       is read as

        (1, undef, undef, " ", 2)

       Note that this affects only fields that are  originally  empty,  not fields that are empty
       after stripping allowed whitespace. YMMV.

       allow_whitespace

        my $csv = Text::CSV_XS->new ({ allow_whitespace => 1 });
                $csv->allow_whitespace (0);
        my $f = $csv->allow_whitespace;

       When this option is set to true,  the whitespace  ("TAB"'s and "SPACE"'s) surrounding  the
       separation character  is removed when parsing.  If either "TAB" or "SPACE" is one of the
       three characters "sep_char", "quote_char", or "escape_char" it will not be considered
       whitespace.

       Now lines like:

        1 , "foo" , bar , 3 , zapp

       are parsed as valid "CSV", even though it violates the "CSV" specs.

       Note that  all  whitespace is stripped from both  start and  end of each field.  That
       would make it  more than a feature to enable parsing bad "CSV" lines, as

        1,   2.0,  3,   ape  , monkey

       will now be parsed as

        ("1", "2.0", "3", "ape", "monkey")

       even if the original line was perfectly acceptable "CSV".

       allow_loose_quotes

        my $csv = Text::CSV_XS->new ({ allow_loose_quotes => 1 });
                $csv->allow_loose_quotes (0);
        my $f = $csv->allow_loose_quotes;

       By default, parsing unquoted fields containing "quote_char" characters like

        1,foo "bar" baz,42

       would result in parse error 2034.  Though it is still bad practice to allow this format,
       we  cannot  help  the  fact  that  some  vendors  make  their applications spit out lines
       styled this way.

       If there is really bad "CSV" data, like

        1,"foo "bar" baz",42

       or

        1,""foo bar baz"",42

       there is a way to get this data-line parsed and leave the quotes inside the quoted field
       as-is.  This can be achieved by setting  "allow_loose_quotes" AND making sure that the
       "escape_char" is  not equal to "quote_char".

       allow_loose_escapes

        my $csv = Text::CSV_XS->new ({ allow_loose_escapes => 1 });
                $csv->allow_loose_escapes (0);
        my $f = $csv->allow_loose_escapes;

       Parsing fields  that  have  "escape_char"  characters that escape characters that do not
       need to be escaped, like:

        my $csv = Text::CSV_XS->new ({ escape_char => "\\" });
        $csv->parse (qq{1,"my bar\'s",baz,42});

       would result in parse error 2025.   Though it is bad practice to allow this format,  this
       attribute enables you to treat all escape character sequences equal.

       allow_unquoted_escape

        my $csv = Text::CSV_XS->new ({ allow_unquoted_escape => 1 });
                $csv->allow_unquoted_escape (0);
        my $f = $csv->allow_unquoted_escape;

       A backward compatibility issue where "escape_char" differs from "quote_char"  prevents
       "escape_char" to be in the first position of a field.  If "quote_char" is equal to the
       default """ and "escape_char" is set to "\", this would be illegal:

        1,\0,2

       Setting this attribute to 1  might help to overcome issues with backward compatibility and
       allow this style.

       always_quote

        my $csv = Text::CSV_XS->new ({ always_quote => 1 });
                $csv->always_quote (0);
        my $f = $csv->always_quote;

       By default the generated fields are quoted only if they need to be.  For example, if they
       contain the separator character. If you set this attribute to 1 then all defined fields
       will be quoted. ("undef" fields are not quoted, see "blank_is_undef"). This makes it quite
       often easier to handle exported data in external applications.   (Poor creatures who are
       better to use Text::CSV_XS. :)

       quote_space

        my $csv = Text::CSV_XS->new ({ quote_space => 1 });
                $csv->quote_space (0);
        my $f = $csv->quote_space;

       By default,  a space in a field would trigger quotation.  As no rule exists this to be
       forced in "CSV",  nor any for the opposite, the default is true for safety.   You can
       exclude the space  from this trigger  by setting this attribute to 0.

       quote_empty

        my $csv = Text::CSV_XS->new ({ quote_empty => 1 });
                $csv->quote_empty (0);
        my $f = $csv->quote_empty;

       By default the generated fields are quoted only if they need to be.   An empty (defined)
       field does not need quotation. If you set this attribute to 1 then empty defined fields
       will be quoted.  ("undef" fields are not quoted, see "blank_is_undef"). See also
       "always_quote".

       quote_binary

        my $csv = Text::CSV_XS->new ({ quote_binary => 1 });
                $csv->quote_binary (0);
        my $f = $csv->quote_binary;

       By default,  all "unsafe" bytes inside a string cause the combined field to be quoted.  By
       setting this attribute to 0, you can disable that trigger for bytes >= 0x7F.

       escape_null

        my $csv = Text::CSV_XS->new ({ escape_null => 1 });
                $csv->escape_null (0);
        my $f = $csv->escape_null;

       By default, a "NULL" byte in a field would be escaped. This option enables you to treat
       the  "NULL"  byte as a simple binary character in binary mode (the "{ binary => 1 }" is
       set).  The default is true.  You can prevent "NULL" escapes by setting this attribute to
       0.

       When the "escape_char" attribute is set to undefined,  this attribute will be set to
       false.

       The default setting will encode "=\x00=" as

        "="0="

       With "escape_null" set, this will result in

        "=\x00="

       The default when using the "csv" function is "false".

       For backward compatibility reasons,  the deprecated old name  "quote_null" is still
       recognized.

       keep_meta_info

        my $csv = Text::CSV_XS->new ({ keep_meta_info => 1 });
                $csv->keep_meta_info (0);
        my $f = $csv->keep_meta_info;

       By default, the parsing of input records is as simple and fast as possible.  However,
       some parsing information - like quotation of the original field - is lost in that process.
       Setting this flag to true enables retrieving that information after parsing with  the
       methods  "meta_info",  "is_quoted", and "is_binary" described below.  Default is false for
       performance.

       If you set this attribute to a value greater than 9,   then you can control output
       quotation style like it was used in the input of the the last parsed record (unless
       quotation was added because of other reasons).

        my $csv = Text::CSV_XS->new ({
           binary         => 1,
           keep_meta_info => 1,
           quote_space    => 0,
           });

        my $row = $csv->parse (q{1,,"", ," ",f,"g","h""h",help,"help"});

        $csv->print (*STDOUT, \@row);
        # 1,,, , ,f,g,"h""h",help,help
        $csv->keep_meta_info (11);
        $csv->print (*STDOUT, \@row);
        # 1,,"", ," ",f,"g","h""h",help,"help"

       undef_str

        my $csv = Text::CSV_XS->new ({ undef_str => "\\N" });
                $csv->undef_str (undef);
        my $s = $csv->undef_str;

       This attribute optionally defines the output of undefined fields. The value passed is not
       changed at all, so if it needs quotation, the quotation needs to be included in the value
       of the attribute.  Use with caution, as passing a value like  ",",,,,"""  will for sure
       mess up your output. The default for this attribute is "undef", meaning no special
       treatment.

       This attribute is useful when exporting  CSV data  to be imported in custom loaders, like
       for MySQL, that recognize special sequences for "NULL" data.

       This attribute has no meaning when parsing CSV data.

       comment_str

        my $csv = Text::CSV_XS->new ({ comment_str => "#" });
                $csv->comment_str (undef);
        my $s = $csv->comment_str;

       This attribute optionally defines a string to be recognized as comment.  If this attribute
       is defined,   all lines starting with this sequence will not be parsed as CSV but skipped
       as comment.

       This attribute has no meaning when generating CSV.

       Comment strings that start with any of the special characters/sequences are not supported
       (so it cannot start with any of "sep_char", "quote_char", "escape_char", "sep", "quote",
       or "eol").

       For convenience, "comment" is an alias for "comment_str".

       verbatim

        my $csv = Text::CSV_XS->new ({ verbatim => 1 });
                $csv->verbatim (0);
        my $f = $csv->verbatim;

       This is a quite controversial attribute to set,  but makes some hard things possible.

       The rationale behind this attribute is to tell the parser that the normally special
       characters newline ("NL") and Carriage Return ("CR")  will not be special when this flag
       is set,  and be dealt with  as being ordinary binary characters. This will ease working
       with data with embedded newlines.

       When  "verbatim"  is used with  "getline",  "getline"  auto-"chomp"'s every line.

       Imagine a file format like

        M^^Hans^Janssen^Klas 2\n2A^Ja^11-06-2007#\r\n

       where, the line ending is a very specific "#\r\n", and the sep_char is a "^" (caret).
       None of the fields is quoted,   but embedded binary data is likely to be present. With the
       specific line ending, this should not be too hard to detect.

       By default,  Text::CSV_XS'  parse function is instructed to only know about "\n" and "\r"
       to be legal line endings,  and so has to deal with the embedded newline as a real
       "end-of-line",  so it can scan the next line if binary is true, and the newline is inside
       a quoted field. With this option, we tell "parse" to parse the line as if "\n" is just
       nothing more than a binary character.

       For "parse" this means that the parser has no more idea about line ending and "getline"
       "chomp"s line endings on reading.

       types

       A set of column types; the attribute is immediately passed to the "types" method.

       callbacks

       See the "Callbacks" section below.

       accessors

       To sum it up,

        $csv = Text::CSV_XS->new ();

       is equivalent to

        $csv = Text::CSV_XS->new ({
            eol                   => undef, # \r, \n, or \r\n
            sep_char              => ',',
            sep                   => undef,
            quote_char            => '"',
            quote                 => undef,
            escape_char           => '"',
            binary                => 0,
            decode_utf8           => 1,
            auto_diag             => 0,
            diag_verbose          => 0,
            blank_is_undef        => 0,
            empty_is_undef        => 0,
            allow_whitespace      => 0,
            allow_loose_quotes    => 0,
            allow_loose_escapes   => 0,
            allow_unquoted_escape => 0,
            always_quote          => 0,
            quote_empty           => 0,
            quote_space           => 1,
            escape_null           => 1,
            quote_binary          => 1,
            keep_meta_info        => 0,
            strict                => 0,
            skip_empty_rows       => 0,
            formula               => 0,
            verbatim              => 0,
            undef_str             => undef,
            comment_str           => undef,
            types                 => undef,
            callbacks             => undef,
            });

       For all of the above mentioned flags, an accessor method is available where you can
       inquire the current value, or change the value

        my $quote = $csv->quote_char;
        $csv->binary (1);

       It is not wise to change these settings halfway through writing "CSV" data to a stream. If
       however you want to create a new stream using the available "CSV" object, there is no harm
       in changing them.

       If the "new" constructor call fails,  it returns "undef",  and makes the fail reason
       available through the "error_diag" method.

        $csv = Text::CSV_XS->new ({ ecs_char => 1 }) or
            die "".Text::CSV_XS->error_diag ();

       "error_diag" will return a string like

        "INI - Unknown attribute 'ecs_char'"

   known_attributes
        @attr = Text::CSV_XS->known_attributes;
        @attr = Text::CSV_XS::known_attributes;
        @attr = $csv->known_attributes;

       This method will return an ordered list of all the supported  attributes as described
       above.   This can be useful for knowing what attributes are valid in classes that use or
       extend Text::CSV_XS.

   print
        $status = $csv->print ($fh, $colref);

       Similar to  "combine" + "string" + "print",  but much more efficient.  It expects an array
       ref as input  (not an array!)  and the resulting string is not really  created,  but
       immediately  written  to the  $fh  object, typically an IO handle or any other object that
       offers a "print" method.

       For performance reasons  "print"  does not create a result string,  so all "string",
       "status", "fields", and "error_input" methods will return undefined information after
       executing this method.

       If $colref is "undef"  (explicit,  not through a variable argument) and "bind_columns"
       was used to specify fields to be printed,  it is possible to make performance
       improvements, as otherwise data would have to be copied as arguments to the method call:

        $csv->bind_columns (\($foo, $bar));
        $status = $csv->print ($fh, undef);

       A short benchmark

        my @data = ("aa" .. "zz");
        $csv->bind_columns (\(@data));

        $csv->print ($fh, [ @data ]);   # 11800 recs/sec
        $csv->print ($fh,  \@data  );   # 57600 recs/sec
        $csv->print ($fh,   undef  );   # 48500 recs/sec

   say
        $status = $csv->say ($fh, $colref);

       Like "print", but "eol" defaults to "$\".

   print_hr
        $csv->print_hr ($fh, $ref);

       Provides an easy way  to print a  $ref  (as fetched with "getline_hr") provided the column
       names are set with "column_names".

       It is just a wrapper method with basic parameter checks over

        $csv->print ($fh, [ map { $ref->{$_} } $csv->column_names ]);

   combine
        $status = $csv->combine (@fields);

       This method constructs a "CSV" record from  @fields,  returning success or failure.
       Failure can result from lack of arguments or an argument that contains an invalid
       character.   Upon success,  "string" can be called to retrieve the resultant "CSV" string.
       Upon failure,  the value returned by "string" is undefined and "error_input" could be
       called to retrieve the invalid argument.

   string
        $line = $csv->string ();

       This method returns the input to  "parse"  or the resultant "CSV" string of "combine",
       whichever was called more recently.

   getline
        $colref = $csv->getline ($fh);

       This is the counterpart to  "print",  as "parse"  is the counterpart to "combine":  it
       parses a row from the $fh  handle using the "getline" method associated with $fh  and
       parses this row into an array ref.  This array ref is returned by the function or "undef"
       for failure.  When $fh does not support "getline", you are likely to hit errors.

       When fields are bound with "bind_columns" the return value is a reference to an empty
       list.

       The "string", "fields", and "status" methods are meaningless again.

   getline_all
        $arrayref = $csv->getline_all ($fh);
        $arrayref = $csv->getline_all ($fh, $offset);
        $arrayref = $csv->getline_all ($fh, $offset, $length);

       This will return a reference to a list of getline ($fh) results.  In this call,
       "keep_meta_info" is disabled.  If $offset is negative, as with "splice", only the last
       "abs ($offset)" records of $fh are taken into consideration.

       Given a CSV file with 10 lines:

        lines call
        ----- ---------------------------------------------------------
        0..9  $csv->getline_all ($fh)         # all
        0..9  $csv->getline_all ($fh,  0)     # all
        8..9  $csv->getline_all ($fh,  8)     # start at 8
        -     $csv->getline_all ($fh,  0,  0) # start at 0 first 0 rows
        0..4  $csv->getline_all ($fh,  0,  5) # start at 0 first 5 rows
        4..5  $csv->getline_all ($fh,  4,  2) # start at 4 first 2 rows
        8..9  $csv->getline_all ($fh, -2)     # last 2 rows
        6..7  $csv->getline_all ($fh, -4,  2) # first 2 of last  4 rows

   getline_hr
       The "getline_hr" and "column_names" methods work together  to allow you to have rows
       returned as hashrefs.  You must call "column_names" first to declare your column names.

        $csv->column_names (qw( code name price description ));
        $hr = $csv->getline_hr ($fh);
        print "Price for $hr->{name} is $hr->{price} EUR\n";

       "getline_hr" will croak if called before "column_names".

       Note that  "getline_hr"  creates a hashref for every row and will be much slower than the
       combined use of "bind_columns"  and "getline" but still offering the same easy to use
       hashref inside the loop:

        my @cols = @{$csv->getline ($fh)};
        $csv->column_names (@cols);
        while (my $row = $csv->getline_hr ($fh)) {
            print $row->{price};
            }

       Could easily be rewritten to the much faster:

        my @cols = @{$csv->getline ($fh)};
        my $row = {};
        $csv->bind_columns (\@{$row}{@cols});
        while ($csv->getline ($fh)) {
            print $row->{price};
            }

       Your mileage may vary for the size of the data and the number of rows. With perl-5.14.2
       the comparison for a 100_000 line file with 14 columns:

                   Rate hashrefs getlines
        hashrefs 1.00/s       --     -76%
        getlines 4.15/s     313%       --

   getline_hr_all
        $arrayref = $csv->getline_hr_all ($fh);
        $arrayref = $csv->getline_hr_all ($fh, $offset);
        $arrayref = $csv->getline_hr_all ($fh, $offset, $length);

       This will return a reference to a list of   getline_hr ($fh) results.  In this call,
       "keep_meta_info" is disabled.

   parse
        $status = $csv->parse ($line);

       This method decomposes a  "CSV"  string into fields,  returning success or failure.
       Failure can result from a lack of argument  or the given  "CSV" string is improperly
       formatted.   Upon success, "fields" can be called to retrieve the decomposed fields. Upon
       failure calling "fields" will return undefined data and  "error_input"  can be called to
       retrieve  the invalid argument.

       You may use the "types"  method for setting column types.  See "types"' description below.

       The $line argument is supposed to be a simple scalar. Everything else is supposed to croak
       and set error 1500.

   fragment
       This function tries to implement RFC7111  (URI Fragment Identifiers for the text/csv Media
       Type) - https://datatracker.ietf.org/doc/html/rfc7111

        my $AoA = $csv->fragment ($fh, $spec);

       In specifications,  "*" is used to specify the last item, a dash ("-") to indicate a
       range.   All indices are 1-based:  the first row or column has index 1. Selections can be
       combined with the semi-colon (";").

       When using this method in combination with  "column_names",  the returned reference  will
       point to a  list of hashes  instead of a  list of lists.  A disjointed  cell-based
       combined selection  might return rows with different number of columns making the use of
       hashes unpredictable.

        $csv->column_names ("Name", "Age");
        my $AoH = $csv->fragment ($fh, "col=3;8");

       If the "after_parse" callback is active,  it is also called on every line parsed and
       skipped before the fragment.

       row
          row=4
          row=5-7
          row=6-*
          row=1-2;4;6-*

       col
          col=2
          col=1-3
          col=4-*
          col=1-2;4;7-*

       cell
         In cell-based selection, the comma (",") is used to pair row and column

          cell=4,1

         The range operator ("-") using "cell"s can be used to define top-left and bottom-right
         "cell" location

          cell=3,1-4,6

         The "*" is only allowed in the second part of a pair

          cell=3,2-*,2    # row 3 till end, only column 2
          cell=3,2-3,*    # column 2 till end, only row 3
          cell=3,2-*,*    # strip row 1 and 2, and column 1

         Cells and cell ranges may be combined with ";", possibly resulting in rows with
         different numbers of columns

          cell=1,1-2,2;3,3-4,4;1,4;4,1

         Disjointed selections will only return selected cells.   The cells that are not
         specified  will  not  be  included  in the  returned set,  not even as "undef".  As an
         example given a "CSV" like

          11,12,13,...19
          21,22,...28,29
          :            :
          91,...97,98,99

         with "cell=1,1-2,2;3,3-4,4;1,4;4,1" will return:

          11,12,14
          21,22
          33,34
          41,43,44

         Overlapping cell-specs will return those cells only once, So
         "cell=1,1-3,3;2,2-4,4;2,3;4,2" will return:

          11,12,13
          21,22,23,24
          31,32,33,34
          42,43,44

       RFC7111 <https://datatracker.ietf.org/doc/html/rfc7111> does  not  allow different types
       of specs to be combined   (either "row" or "col" or "cell").  Passing an invalid fragment
       specification will croak and set error 2013.

   column_names
       Set the "keys" that will be used in the  "getline_hr"  calls.  If no keys (column names)
       are passed, it will return the current setting as a list.

       "column_names" accepts a list of scalars  (the column names)  or a single array_ref, so
       you can pass the return value from "getline" too:

        $csv->column_names ($csv->getline ($fh));

       "column_names" does no checking on duplicates at all, which might lead to unexpected
       results.   Undefined entries will be replaced with the string "\cAUNDEF\cA", so

        $csv->column_names (undef, "", "name", "name");
        $hr = $csv->getline_hr ($fh);

       will set "$hr->{"\cAUNDEF\cA"}" to the 1st field,  "$hr->{""}" to the 2nd field, and
       "$hr->{name}" to the 4th field,  discarding the 3rd field.

       "column_names" croaks on invalid arguments.

   header
       This method does NOT work in perl-5.6.x

       Parse the CSV header and set "sep", column_names and encoding.

        my @hdr = $csv->header ($fh);
        $csv->header ($fh, { sep_set => [ ";", ",", "|", "\t" ] });
        $csv->header ($fh, { detect_bom => 1, munge_column_names => "lc" });

       The first argument should be a file handle.

       This method resets some object properties,  as it is supposed to be invoked only once per
       file or stream.  It will leave attributes "column_names" and "bound_columns" alone if
       setting column names is disabled. Reading headers on previously process objects might fail
       on perl-5.8.0 and older.

       Assuming that the file opened for parsing has a header, and the header does not contain
       problematic characters like embedded newlines,   read the first line from the open handle
       then auto-detect whether the header separates the column names with a character from the
       allowed separator list.

       If any of the allowed separators matches,  and none of the other allowed separators match,
       set  "sep"  to that  separator  for the current CSV_XS instance and use it to parse the
       first line, map those to lowercase, and use that to set the instance "column_names":

        my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
        open my $fh, "<", "file.csv";
        binmode $fh; # for Windows
        $csv->header ($fh);
        while (my $row = $csv->getline_hr ($fh)) {
            ...
            }

       If the header is empty,  contains more than one unique separator out of the allowed set,
       contains empty fields,   or contains identical fields  (after folding), it will croak with
       error 1010, 1011, 1012, or 1013 respectively.

       If the header contains embedded newlines or is not valid  CSV  in any other way, this
       method will croak and leave the parse error untouched.

       A successful call to "header"  will always set the  "sep"  of the $csv object. This
       behavior can not be disabled.

       return value

       On error this method will croak.

       In list context,  the headers will be returned whether they are used to set "column_names"
       or not.

       In scalar context, the instance itself is returned.  Note: the values as found in the
       header will effectively be  lost if  "set_column_names" is false.

       Options

       sep_set
          $csv->header ($fh, { sep_set => [ ";", ",", "|", "\t" ] });

         The list of legal separators defaults to "[ ";", "," ]" and can be changed by this
         option.  As this is probably the most often used option,  it can be passed on its own as
         an unnamed argument:

          $csv->header ($fh, [ ";", ",", "|", "\t", "::", "\x{2063}" ]);

         Multi-byte  sequences are allowed,  both multi-character and  Unicode.  See "sep".

       detect_bom
          $csv->header ($fh, { detect_bom => 1 });

         The default behavior is to detect if the header line starts with a BOM.  If the header
         has a BOM, use that to set the encoding of $fh.  This default behavior can be disabled
         by passing a false value to "detect_bom".

         Supported encodings from BOM are: UTF-8, UTF-16BE, UTF-16LE, UTF-32BE,  and UTF-32LE.
         BOM also supports UTF-1, UTF-EBCDIC, SCSU, BOCU-1,  and GB-18030 but Encode does not
         (yet). UTF-7 is not supported.

         If a supported BOM was detected as start of the stream, it is stored in the object
         attribute "ENCODING".

          my $enc = $csv->{ENCODING};

         The encoding is used with "binmode" on $fh.

         If the handle was opened in a (correct) encoding,  this method will  not alter the
         encoding, as it checks the leading bytes of the first line. In case the stream starts
         with a decoded BOM ("U+FEFF"), "{ENCODING}" will be "" (empty) instead of the default
         "undef".

       munge_column_names
         This option offers the means to modify the column names into something that is most
         useful to the application.   The default is to map all column names to lower case.

          $csv->header ($fh, { munge_column_names => "lc" });

         The following values are available:

           lc     - lower case
           uc     - upper case
           db     - valid DB field names
           none   - do not change
           \%hash - supply a mapping
           \&cb   - supply a callback

         Lower case
            $csv->header ($fh, { munge_column_names => "lc" });

           The header is changed to all lower-case

            $_ = lc;

         Upper case
            $csv->header ($fh, { munge_column_names => "uc" });

           The header is changed to all upper-case

            $_ = uc;

         Literal
            $csv->header ($fh, { munge_column_names => "none" });

         Hash
            $csv->header ($fh, { munge_column_names => { foo => "sombrero" });

           if a value does not exist, the original value is used unchanged

         Database
            $csv->header ($fh, { munge_column_names => "db" });

           - lower-case

           - all sequences of non-word characters are replaced with an underscore

           - all leading underscores are removed

            $_ = lc (s/\W+/_/gr =~ s/^_+//r);

         Callback
            $csv->header ($fh, { munge_column_names => sub { fc } });
            $csv->header ($fh, { munge_column_names => sub { "column_".$col++ } });
            $csv->header ($fh, { munge_column_names => sub { lc (s/\W+/_/gr) } });

           As this callback is called in a "map", you can use $_ directly.

       set_column_names
          $csv->header ($fh, { set_column_names => 1 });

         The default is to set the instances column names using  "column_names" if the method is
         successful,  so subsequent calls to "getline_hr" can return a hash. Disable setting the
         header can be forced by using a false value for this option.

         As described in "return value" above, content is lost in scalar context.

       Validation

       When receiving CSV files from external sources,  this method can be used to protect
       against changes in the layout by restricting to known headers  (and typos in the header
       fields).

        my %known = (
            "record key" => "c_rec",
            "rec id"     => "c_rec",
            "id_rec"     => "c_rec",
            "kode"       => "code",
            "code"       => "code",
            "vaule"      => "value",
            "value"      => "value",
            );
        my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
        open my $fh, "<", $source or die "$source: $!";
        $csv->header ($fh, { munge_column_names => sub {
            s/\s+$//;
            s/^\s+//;
            $known{lc $_} or die "Unknown column '$_' in $source";
            }});
        while (my $row = $csv->getline_hr ($fh)) {
            say join "\t", $row->{c_rec}, $row->{code}, $row->{value};
            }

   bind_columns
       Takes a list of scalar references to be used for output with  "print"  or to store in the
       fields fetched by "getline".  When you do not pass enough references to store the fetched
       fields in, "getline" will fail with error 3006.  If you pass more than there are fields to
       return,  the content of the remaining references is left untouched.

        $csv->bind_columns (\$code, \$name, \$price, \$description);
        while ($csv->getline ($fh)) {
            print "The price of a $name is \x{20ac} $price\n";
            }

       To reset or clear all column binding, call "bind_columns" with the single argument
       "undef". This will also clear column names.

        $csv->bind_columns (undef);

       If no arguments are passed at all, "bind_columns" will return the list of current bindings
       or "undef" if no binds are active.

       Note that in parsing with  "bind_columns",  the fields are set on the fly.  That implies
       that if the third field of a row causes an error  (or this row has just two fields where
       the previous row had more),  the first two fields already have been assigned the values of
       the current row, while the rest of the fields will still hold the values of the previous
       row.  If you want the parser to fail in these cases, use the "strict" attribute.

   eof
        $eof = $csv->eof ();

       If "parse" or  "getline"  was used with an IO stream,  this method will return true (1) if
       the last call hit end of file,  otherwise it will return false ('').  This is useful to
       see the difference between a failure and end of file.

       Note that if the parsing of the last line caused an error,  "eof" is still true.  That
       means that if you are not using "auto_diag", an idiom like

        while (my $row = $csv->getline ($fh)) {
            # ...
            }
        $csv->eof or $csv->error_diag;

       will not report the error. You would have to change that to

        while (my $row = $csv->getline ($fh)) {
            # ...
            }
        +$csv->error_diag and $csv->error_diag;

   types
        $csv->types (\@tref);

       This method is used to force that  (all)  columns are of a given type.  For example, if
       you have an integer column,  two  columns  with  doubles  and a string column, then you
       might do a

        $csv->types ([Text::CSV_XS::IV (),
                      Text::CSV_XS::NV (),
                      Text::CSV_XS::NV (),
                      Text::CSV_XS::PV ()]);

       Column types are used only for decoding columns while parsing,  in other words by the
       "parse" and "getline" methods.

       You can unset column types by doing a

        $csv->types (undef);

       or fetch the current type settings with

        $types = $csv->types ();

       IV  Set field type to integer.

       NV  Set field type to numeric/float.

       PV  Set field type to string.

   fields
        @columns = $csv->fields ();

       This method returns the input to   "combine"  or the resultant decomposed fields of a
       successful "parse", whichever was called more recently.

       Note that the return value is undefined after using "getline", which does not fill the
       data structures returned by "parse".

   meta_info
        @flags = $csv->meta_info ();

       This method returns the "flags" of the input to "combine" or the flags of the resultant
       decomposed fields of  "parse",   whichever was called more recently.

       For each field,  a meta_info field will hold  flags that  inform  something about  the
       field  returned  by  the  "fields"  method or  passed to  the "combine" method. The flags
       are bit-wise-"or"'d like:

       " "0x0001
         The field was quoted.

       " "0x0002
         The field was binary.

       See the "is_***" methods below.

   is_quoted
        my $quoted = $csv->is_quoted ($column_idx);

       where  $column_idx is the  (zero-based)  index of the column in the last result of
       "parse".

       This returns a true value  if the data in the indicated column was enclosed in
       "quote_char" quotes.  This might be important for fields where content ",20070108," is to
       be treated as a numeric value,  and where ","20070108"," is explicitly marked as character
       string data.

       This method is only valid when "keep_meta_info" is set to a true value.

   is_binary
        my $binary = $csv->is_binary ($column_idx);

       where  $column_idx is the  (zero-based)  index of the column in the last result of
       "parse".

       This returns a true value if the data in the indicated column contained any byte in the
       range "[\x00-\x08,\x10-\x1F,\x7F-\xFF]".

       This method is only valid when "keep_meta_info" is set to a true value.

   is_missing
        my $missing = $csv->is_missing ($column_idx);

       where  $column_idx is the  (zero-based)  index of the column in the last result of
       "getline_hr".

        $csv->keep_meta_info (1);
        while (my $hr = $csv->getline_hr ($fh)) {
            $csv->is_missing (0) and next; # This was an empty line
            }

       When using  "getline_hr",  it is impossible to tell if the  parsed fields are "undef"
       because they where not filled in the "CSV" stream  or because they were not read at all,
       as all the fields defined by "column_names" are set in the hash-ref.    If you still need
       to know if all fields in each row are provided, you should enable "keep_meta_info" so you
       can check the flags.

       If  "keep_meta_info"  is "false",  "is_missing"  will always return "undef", regardless of
       $column_idx being valid or not. If this attribute is "true" it will return either 0 (the
       field is present) or 1 (the field is missing).

       A special case is the empty line.  If the line is completely empty -  after dealing with
       the flags - this is still a valid CSV line:  it is a record of just one single empty
       field. However, if "keep_meta_info" is set, invoking "is_missing" with index 0 will now
       return true.

   status
        $status = $csv->status ();

       This method returns the status of the last invoked "combine" or "parse" call. Status is
       success (true: 1) or failure (false: "undef" or 0).

       Note that as this only keeps track of the status of above mentioned methods, you are
       probably looking for "error_diag" instead.

   error_input
        $bad_argument = $csv->error_input ();

       This method returns the erroneous argument (if it exists) of "combine" or "parse",
       whichever was called more recently.  If the last invocation was successful, "error_input"
       will return "undef".

       Depending on the type of error, it might also hold the data for the last error-input of
       "getline".

   error_diag
        Text::CSV_XS->error_diag ();
        $csv->error_diag ();
        $error_code               = 0  + $csv->error_diag ();
        $error_str                = "" . $csv->error_diag ();
        ($cde, $str, $pos, $rec, $fld) = $csv->error_diag ();

       If (and only if) an error occurred,  this function returns  the diagnostics of that error.

       If called in void context,  this will print the internal error code and the associated
       error message to STDERR.

       If called in list context,  this will return  the error code  and the error message in
       that order.  If the last error was from parsing, the rest of the values returned are a
       best guess at the location  within the line  that was being parsed. Their values are
       1-based.  The position currently is index of the byte at which the parsing failed in the
       current record. It might change to be the index of the current character in a later
       release. The records is the index of the record parsed by the csv instance. The field
       number is the index of the field the parser thinks it is currently  trying to  parse. See
       examples/csv-check for how this can be used.

       If called in  scalar context,  it will return  the diagnostics  in a single scalar, a-la
       $!.  It will contain the error code in numeric context, and the diagnostics message in
       string context.

       When called as a class method or a  direct function call,  the  diagnostics are that of
       the last "new" call.

   record_number
        $recno = $csv->record_number ();

       Returns the records parsed by this csv instance.  This value should be more accurate than
       $. when embedded newlines come in play. Records written by this instance are not counted.

   SetDiag
        $csv->SetDiag (0);

       Use to reset the diagnostics if you are dealing with errors.

FUNCTIONS
   csv
       This function is not exported by default and should be explicitly requested:

        use Text::CSV_XS qw( csv );

       This is a high-level function that aims at simple (user) interfaces.  This can be used to
       read/parse a "CSV" file or stream (the default behavior) or to produce a file or write to
       a stream (define the  "out"  attribute).  It returns an array- or hash-reference on
       parsing (or "undef" on fail) or the numeric value of  "error_diag"  on writing.  When this
       function fails you can get to the error using the class call to "error_diag"

        my $aoa = csv (in => "test.csv") or
            die Text::CSV_XS->error_diag;

       This function takes the arguments as key-value pairs. This can be passed as a list or as
       an anonymous hash:

        my $aoa = csv (  in => "test.csv", sep_char => ";");
        my $aoh = csv ({ in => $fh, headers => "auto" });

       The arguments passed consist of two parts:  the arguments to "csv" itself and the optional
       attributes to the  "CSV"  object used inside the function as enumerated and explained in
       "new".

       If not overridden, the default option used for CSV is

        auto_diag   => 1
        escape_null => 0

       The option that is always set and cannot be altered is

        binary      => 1

       As this function will likely be used in one-liners,  it allows  "quote" to be abbreviated
       as "quo",  and  "escape_char" to be abbreviated as  "esc" or "escape".

       Alternative invocations:

        my $aoa = Text::CSV_XS::csv (in => "file.csv");

        my $csv = Text::CSV_XS->new ();
        my $aoa = $csv->csv (in => "file.csv");

       In the latter case, the object attributes are used from the existing object and the
       attribute arguments in the function call are ignored:

        my $csv = Text::CSV_XS->new ({ sep_char => ";" });
        my $aoh = $csv->csv (in => "file.csv", bom => 1);

       will parse using ";" as "sep_char", not ",".

       in

       Used to specify the source.  "in" can be a file name (e.g. "file.csv"), which will be
       opened for reading  and closed when finished,  a file handle (e.g.  $fh or "FH"),  a
       reference to a glob (e.g. "\*ARGV"),  the glob itself (e.g. *STDIN), or a reference to a
       scalar (e.g. "\q{1,2,"csv"}").

       When used with "out", "in" should be a reference to a CSV structure (AoA or AoH)  or a
       CODE-ref that returns an array-reference or a hash-reference.  The code-ref will be
       invoked with no arguments.

        my $aoa = csv (in => "file.csv");

        open my $fh, "<", "file.csv";
        my $aoa = csv (in => $fh);

        my $csv = [ [qw( Foo Bar )], [ 1, 2 ], [ 2, 3 ]];
        my $err = csv (in => $csv, out => "file.csv");

       If called in void context without the "out" attribute, the resulting ref will be used as
       input to a subsequent call to csv:

        csv (in => "file.csv", filter => { 2 => sub { length > 2 }})

       will be a shortcut to

        csv (in => csv (in => "file.csv", filter => { 2 => sub { length > 2 }}))

       where, in the absence of the "out" attribute, this is a shortcut to

        csv (in  => csv (in => "file.csv", filter => { 2 => sub { length > 2 }}),
             out => *STDOUT)

       out

        csv (in => $aoa, out => "file.csv");
        csv (in => $aoa, out => $fh);
        csv (in => $aoa, out =>   STDOUT);
        csv (in => $aoa, out =>  *STDOUT);
        csv (in => $aoa, out => \*STDOUT);
        csv (in => $aoa, out => \my $data);
        csv (in => $aoa, out =>  undef);
        csv (in => $aoa, out => \"skip");

        csv (in => $fh,  out => \@aoa);
        csv (in => $fh,  out => \@aoh, bom => 1);
        csv (in => $fh,  out => \%hsh, key => "key");

       In output mode, the default CSV options when producing CSV are

        eol       => "\r\n"

       The "fragment" attribute is ignored in output mode.

       "out" can be a file name  (e.g.  "file.csv"),  which will be opened for writing and closed
       when finished,  a file handle (e.g. $fh or "FH"),  a reference to a glob (e.g.
       "\*STDOUT"),  the glob itself (e.g. *STDOUT), or a reference to a scalar (e.g. "\my
       $data").

        csv (in => sub { $sth->fetch },            out => "dump.csv");
        csv (in => sub { $sth->fetchrow_hashref }, out => "dump.csv",
             headers => $sth->{NAME_lc});

       When a code-ref is used for "in", the output is generated  per invocation, so no buffering
       is involved. This implies that there is no size restriction on the number of records. The
       "csv" function ends when the coderef returns a false value.

       If "out" is set to a reference of the literal string "skip", the output will be suppressed
       completely,  which might be useful in combination with a filter for side effects only.

        my %cache;
        csv (in    => "dump.csv",
             out   => \"skip",
             on_in => sub { $cache{$_[1][1]}++ });

       Currently,  setting "out" to any false value  ("undef", "", 0) will be equivalent to
       "\"skip"".

       If the "in" argument point to something to parse, and the "out" is set to a reference to
       an "ARRAY" or a "HASH", the output is appended to the data in the existing reference. The
       result of the parse should match what exists in the reference passed. This might come
       handy when you have to parse a set of files with similar content (like data stored per
       period) and you want to collect that into a single data structure:

        my %hash;
        csv (in => $_, out => \%hash, key => "id") for sort glob "foo-[0-9]*.csv";

        my @list; # List of arrays
        csv (in => $_, out => \@list)              for sort glob "foo-[0-9]*.csv";

        my @list; # List of hashes
        csv (in => $_, out => \@list, bom => 1)    for sort glob "foo-[0-9]*.csv";

       encoding

       If passed,  it should be an encoding accepted by the  ":encoding()" option to "open".
       There is no default value. This attribute does not work in perl 5.6.x.  "encoding" can be
       abbreviated to "enc" for ease of use in command line invocations.

       If "encoding" is set to the literal value "auto", the method "header" will be invoked on
       the opened stream to check if there is a BOM and set the encoding accordingly.   This is
       equal to passing a true value in the option "detect_bom".

       Encodings can be stacked, as supported by "binmode":

        # Using PerlIO::via::gzip
        csv (in       => \@csv,
             out      => "test.csv:via.gz",
             encoding => ":via(gzip):encoding(utf-8)",
             );
        $aoa = csv (in => "test.csv:via.gz",  encoding => ":via(gzip)");

        # Using PerlIO::gzip
        csv (in       => \@csv,
             out      => "test.csv:via.gz",
             encoding => ":gzip:encoding(utf-8)",
             );
        $aoa = csv (in => "test.csv:gzip.gz", encoding => ":gzip");

       detect_bom

       If  "detect_bom"  is given, the method  "header"  will be invoked on the opened stream to
       check if there is a BOM and set the encoding accordingly.

       "detect_bom" can be abbreviated to "bom".

       This is the same as setting "encoding" to "auto".

       Note that as the method  "header" is invoked,  its default is to also set the headers.

       headers

       If this attribute is not given, the default behavior is to produce an array of arrays.

       If "headers" is supplied,  it should be an anonymous list of column names, an anonymous
       hashref, a coderef, or a literal flag:  "auto", "lc", "uc", or "skip".

       skip
         When "skip" is used, the header will not be included in the output.

          my $aoa = csv (in => $fh, headers => "skip");

       auto
         If "auto" is used, the first line of the "CSV" source will be read as the list of field
         headers and used to produce an array of hashes.

          my $aoh = csv (in => $fh, headers => "auto");

       lc
         If "lc" is used,  the first line of the  "CSV" source will be read as the list of field
         headers mapped to  lower case and used to produce an array of hashes. This is a
         variation of "auto".

          my $aoh = csv (in => $fh, headers => "lc");

       uc
         If "uc" is used,  the first line of the  "CSV" source will be read as the list of field
         headers mapped to  upper case and used to produce an array of hashes. This is a
         variation of "auto".

          my $aoh = csv (in => $fh, headers => "uc");

       CODE
         If a coderef is used,  the first line of the  "CSV" source will be read as the list of
         mangled field headers in which each field is passed as the only argument to the coderef.
         This list is used to produce an array of hashes.

          my $aoh = csv (in      => $fh,
                         headers => sub { lc ($_[0]) =~ s/kode/code/gr });

         this example is a variation of using "lc" where all occurrences of "kode" are replaced
         with "code".

       ARRAY
         If  "headers"  is an anonymous list,  the entries in the list will be used as field
         names. The first line is considered data instead of headers.

          my $aoh = csv (in => $fh, headers => [qw( Foo Bar )]);
          csv (in => $aoa, out => $fh, headers => [qw( code description price )]);

       HASH
         If "headers" is a hash reference, this implies "auto", but header fields that exist as
         key in the hashref will be replaced by the value for that key. Given a CSV file like

          post-kode,city,name,id number,fubble
          1234AA,Duckstad,Donald,13,"X313DF"

         using

          csv (headers => { "post-kode" => "pc", "id number" => "ID" }, ...

         will return an entry like

          { pc     => "1234AA",
            city   => "Duckstad",
            name   => "Donald",
            ID     => "13",
            fubble => "X313DF",
            }

       See also "munge_column_names" and "set_column_names".

       munge_column_names

       If "munge_column_names" is set,  the method  "header"  is invoked on the opened stream
       with all matching arguments to detect and set the headers.

       "munge_column_names" can be abbreviated to "munge".

       key

       If passed,  will default  "headers"  to "auto" and return a hashref instead of an array of
       hashes. Allowed values are simple scalars or array-references where the first element is
       the joiner and the rest are the fields to join to combine the key.

        my $ref = csv (in => "test.csv", key => "code");
        my $ref = csv (in => "test.csv", key => [ ":" => "code", "color" ]);

       with test.csv like

        code,product,price,color
        1,pc,850,gray
        2,keyboard,12,white
        3,mouse,5,black

       the first example will return

         { 1   => {
               code    => 1,
               color   => 'gray',
               price   => 850,
               product => 'pc'
               },
           2   => {
               code    => 2,
               color   => 'white',
               price   => 12,
               product => 'keyboard'
               },
           3   => {
               code    => 3,
               color   => 'black',
               price   => 5,
               product => 'mouse'
               }
           }

       the second example will return

         { "1:gray"    => {
               code    => 1,
               color   => 'gray',
               price   => 850,
               product => 'pc'
               },
           "2:white"   => {
               code    => 2,
               color   => 'white',
               price   => 12,
               product => 'keyboard'
               },
           "3:black"   => {
               code    => 3,
               color   => 'black',
               price   => 5,
               product => 'mouse'
               }
           }

       The "key" attribute can be combined with "headers" for "CSV" date that has no header line,
       like

        my $ref = csv (
            in      => "foo.csv",
            headers => [qw( c_foo foo bar description stock )],
            key     =>     "c_foo",
            );

       value

       Used to create key-value hashes.

       Only allowed when "key" is valid. A "value" can be either a single column label or an
       anonymous list of column labels.  In the first case,  the value will be a simple scalar
       value, in the latter case, it will be a hashref.

        my $ref = csv (in => "test.csv", key   => "code",
                                         value => "price");
        my $ref = csv (in => "test.csv", key   => "code",
                                         value => [ "product", "price" ]);
        my $ref = csv (in => "test.csv", key   => [ ":" => "code", "color" ],
                                         value => "price");
        my $ref = csv (in => "test.csv", key   => [ ":" => "code", "color" ],
                                         value => [ "product", "price" ]);

       with test.csv like

        code,product,price,color
        1,pc,850,gray
        2,keyboard,12,white
        3,mouse,5,black

       the first example will return

         { 1 => 850,
           2 =>  12,
           3 =>   5,
           }

       the second example will return

         { 1   => {
               price   => 850,
               product => 'pc'
               },
           2   => {
               price   => 12,
               product => 'keyboard'
               },
           3   => {
               price   => 5,
               product => 'mouse'
               }
           }

       the third example will return

         { "1:gray"    => 850,
           "2:white"   =>  12,
           "3:black"   =>   5,
           }

       the fourth example will return

         { "1:gray"    => {
               price   => 850,
               product => 'pc'
               },
           "2:white"   => {
               price   => 12,
               product => 'keyboard'
               },
           "3:black"   => {
               price   => 5,
               product => 'mouse'
               }
           }

       keep_headers

       When using hashes,  keep the column names into the arrayref passed,  so all headers are
       available after the call in the original order.

        my $aoh = csv (in => "file.csv", keep_headers => \my @hdr);

       This attribute can be abbreviated to "kh" or passed as "keep_column_names".

       This attribute implies a default of "auto" for the "headers" attribute.

       fragment

       Only output the fragment as defined in the "fragment" method. This option is ignored when
       generating "CSV". See "out".

       Combining all of them could give something like

        use Text::CSV_XS qw( csv );
        my $aoh = csv (
            in       => "test.txt",
            encoding => "utf-8",
            headers  => "auto",
            sep_char => "|",
            fragment => "row=3;6-9;15-*",
            );
        say $aoh->[15]{Foo};

       sep_set

       If "sep_set" is set, the method "header" is invoked on the opened stream to detect and set
       "sep_char" with the given set.

       "sep_set" can be abbreviated to "seps".

       Note that as the  "header" method is invoked,  its default is to also set the headers.

       set_column_names

       If  "set_column_names" is passed,  the method "header" is invoked on the opened stream
       with all arguments meant for "header".

       If "set_column_names" is passed as a false value, the content of the first row is only
       preserved if the output is AoA:

       With an input-file like

        bAr,foo
        1,2
        3,4,5

       This call

        my $aoa = csv (in => $file, set_column_names => 0);

       will result in

        [[ "bar", "foo"     ],
         [ "1",   "2"       ],
         [ "3",   "4",  "5" ]]

       and

        my $aoa = csv (in => $file, set_column_names => 0, munge => "none");

       will result in

        [[ "bAr", "foo"     ],
         [ "1",   "2"       ],
         [ "3",   "4",  "5" ]]

   Callbacks
       Callbacks enable actions triggered from the inside of Text::CSV_XS.

       While most of what this enables  can easily be done in an  unrolled loop as described in
       the "SYNOPSIS" callbacks can be used to meet special demands or enhance the "csv"
       function.

       error
          $csv->callbacks (error => sub { $csv->SetDiag (0) });

         the "error"  callback is invoked when an error occurs,  but  only  when "auto_diag" is
         set to a true value. A callback is invoked with the values returned by "error_diag":

          my ($c, $s);

          sub ignore3006 {
              my ($err, $msg, $pos, $recno, $fldno) = @_;
              if ($err == 3006) {
                  # ignore this error
                  ($c, $s) = (undef, undef);
                  Text::CSV_XS->SetDiag (0);
                  }
              # Any other error
              return;
              } # ignore3006

          $csv->callbacks (error => \&ignore3006);
          $csv->bind_columns (\$c, \$s);
          while ($csv->getline ($fh)) {
              # Error 3006 will not stop the loop
              }

       after_parse
          $csv->callbacks (after_parse => sub { push @{$_[1]}, "NEW" });
          while (my $row = $csv->getline ($fh)) {
              $row->[-1] eq "NEW";
              }

         This callback is invoked after parsing with  "getline"  only if no  error occurred.  The
         callback is invoked with two arguments:   the current "CSV" parser object and an array
         reference to the fields parsed.

         The return code of the callback is ignored  unless it is a reference to the string
         "skip", in which case the record will be skipped in "getline_all".

          sub add_from_db {
              my ($csv, $row) = @_;
              $sth->execute ($row->[4]);
              push @$row, $sth->fetchrow_array;
              } # add_from_db

          my $aoa = csv (in => "file.csv", callbacks => {
              after_parse => \&add_from_db });

         This hook can be used for validation:

         FAIL
           Die if any of the records does not validate a rule:

            after_parse => sub {
                $_[1][4] =~ m/^[0-9]{4}\s?[A-Z]{2}$/ or
                    die "5th field does not have a valid Dutch zipcode";
                }

         DEFAULT
           Replace invalid fields with a default value:

            after_parse => sub { $_[1][2] =~ m/^\d+$/ or $_[1][2] = 0 }

         SKIP
           Skip records that have invalid fields (only applies to "getline_all"):

            after_parse => sub { $_[1][0] =~ m/^\d+$/ or return \"skip"; }

       before_print
          my $idx = 1;
          $csv->callbacks (before_print => sub { $_[1][0] = $idx++ });
          $csv->print (*STDOUT, [ 0, $_ ]) for @members;

         This callback is invoked  before printing with  "print"  only if no error occurred.  The
         callback is invoked with two arguments:  the current  "CSV" parser object and an array
         reference to the fields passed.

         The return code of the callback is ignored.

          sub max_4_fields {
              my ($csv, $row) = @_;
              @$row > 4 and splice @$row, 4;
              } # max_4_fields

          csv (in => csv (in => "file.csv"), out => *STDOUT,
              callbacks => { before_print => \&max_4_fields });

         This callback is not active for "combine".

       Callbacks for csv ()

       The "csv" allows for some callbacks that do not integrate in XS internals but only feature
       the "csv" function.

         csv (in        => "file.csv",
              callbacks => {
                  filter       => { 6 => sub { $_ > 15 } },    # first
                  after_parse  => sub { say "AFTER PARSE";  }, # first
                  after_in     => sub { say "AFTER IN";     }, # second
                  on_in        => sub { say "ON IN";        }, # third
                  },
              );

         csv (in        => $aoh,
              out       => "file.csv",
              callbacks => {
                  on_in        => sub { say "ON IN";        }, # first
                  before_out   => sub { say "BEFORE OUT";   }, # second
                  before_print => sub { say "BEFORE PRINT"; }, # third
                  },
              );

       filter
         This callback can be used to filter records.  It is called just after a new record has
         been scanned.  The callback accepts a:

         hashref
           The keys are the index to the row (the field name or field number, 1-based) and the
           values are subs to return a true or false value.

            csv (in => "file.csv", filter => {
                       3 => sub { m/a/ },       # third field should contain an "a"
                       5 => sub { length > 4 }, # length of the 5th field minimal 5
                       });

            csv (in => "file.csv", filter => { foo => sub { $_ > 4 }});

           If the keys to the filter hash contain any character that is not a digit it will also
           implicitly set "headers" to "auto"  unless  "headers"  was already passed as argument.
           When headers are active, returning an array of hashes, the filter is not applicable to
           the header itself.

           All sub results should match, as in AND.

           The context of the callback sets  $_ localized to the field indicated by the filter.
           The two arguments are as with all other callbacks, so the other fields in the current
           row can be seen:

            filter => { 3 => sub { $_ > 100 ? $_[1][1] =~ m/A/ : $_[1][6] =~ m/B/ }}

           If the context is set to return a list of hashes  ("headers" is defined), the current
           record will also be available in the localized %_:

            filter => { 3 => sub { $_ > 100 && $_{foo} =~ m/A/ && $_{bar} < 1000  }}

           If the filter is used to alter the content by changing $_,  make sure that the sub
           returns true in order not to have that record skipped:

            filter => { 2 => sub { $_ = uc }}

           will upper-case the second field, and then skip it if the resulting content evaluates
           to false. To always accept, end with truth:

            filter => { 2 => sub { $_ = uc; 1 }}

         coderef
            csv (in => "file.csv", filter => sub { $n++; 0; });

           If the argument to "filter" is a coderef,  it is an alias or shortcut to a filter on
           column 0:

            csv (filter => sub { $n++; 0 });

           is equal to

            csv (filter => { 0 => sub { $n++; 0 });

         filter-name
            csv (in => "file.csv", filter => "not_blank");
            csv (in => "file.csv", filter => "not_empty");
            csv (in => "file.csv", filter => "filled");

           These are predefined filters

           Given a file like (line numbers prefixed for doc purpose only):

            1:1,2,3
            2:
            3:,
            4:""
            5:,,
            6:, ,
            7:"",
            8:" "
            9:4,5,6

           not_blank
             Filter out the blank lines

             This filter is a shortcut for

              filter => { 0 => sub { @{$_[1]} > 1 or
                          defined $_[1][0] && $_[1][0] ne "" } }

             Due to the implementation,  it is currently impossible to also filter lines that
             consists only of a quoted empty field. These lines are also considered blank lines.

             With the given example, lines 2 and 4 will be skipped.

           not_empty
             Filter out lines where all the fields are empty.

             This filter is a shortcut for

              filter => { 0 => sub { grep { defined && $_ ne "" } @{$_[1]} } }

             A space is not regarded being empty, so given the example data, lines 2, 3, 4, 5,
             and 7 are skipped.

           filled
             Filter out lines that have no visible data

             This filter is a shortcut for

              filter => { 0 => sub { grep { defined && m/\S/ } @{$_[1]} } }

             This filter rejects all lines that not have at least one field that does not
             evaluate to the empty string.

             With the given example data, this filter would skip lines 2 through 8.

         One could also use modules like Types::Standard:

          use Types::Standard -types;

          my $type   = Tuple[Str, Str, Int, Bool, Optional[Num]];
          my $check  = $type->compiled_check;

          # filter with compiled check and warnings
          my $aoa = csv (
             in     => \$data,
             filter => {
                 0 => sub {
                     my $ok = $check->($_[1]) or
                         warn $type->get_message ($_[1]), "\n";
                     return $ok;
                     },
                 },
             );

       after_in
         This callback is invoked for each record after all records have been parsed but before
         returning the reference to the caller.  The hook is invoked with two arguments:  the
         current  "CSV"  parser object  and a  reference to the record.   The reference can be a
         reference to a  HASH  or a reference to an ARRAY as determined by the arguments.

         This callback can also be passed as  an attribute without the  "callbacks" wrapper.

       before_out
         This callback is invoked for each record before the record is printed.  The hook is
         invoked with two arguments:  the current "CSV" parser object and a reference to the
         record.   The reference can be a reference to a  HASH or a reference to an ARRAY as
         determined by the arguments.

         This callback can also be passed as an attribute  without the  "callbacks" wrapper.

         This callback makes the row available in %_ if the row is a hashref.  In this case %_ is
         writable and will change the original row.

       on_in
         This callback acts exactly as the "after_in" or the "before_out" hooks.

         This callback can also be passed as an attribute  without the  "callbacks" wrapper.

         This callback makes the row available in %_ if the row is a hashref.  In this case %_ is
         writable and will change the original row. So e.g. with

           my $aoh = csv (
               in      => \"foo\n1\n2\n",
               headers => "auto",
               on_in   => sub { $_{bar} = 2; },
               );

         $aoh will be:

           [ { foo => 1,
               bar => 2,
               }
             { foo => 2,
               bar => 2,
               }
             ]

       csv
         The function  "csv" can also be called as a method or with an existing Text::CSV_XS
         object. This could help if the function is to be invoked a lot of times and the overhead
         of creating the object internally over  and  over again would be prevented by passing an
         existing instance.

          my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });

          my $aoa = $csv->csv (in => $fh);
          my $aoa = csv (in => $fh, csv => $csv);

         both act the same. Running this 20000 times on a 20 lines CSV file,  showed a 53%
         speedup.

INTERNALS
       Combine (...)
       Parse (...)

       The arguments to these internal functions are deliberately not described or documented in
       order to enable the  module authors make changes it when they feel the need for it.  Using
       them is  highly  discouraged  as  the  API may change in future releases.

EXAMPLES
   Reading a CSV file line by line:
        my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
        open my $fh, "<", "file.csv" or die "file.csv: $!";
        while (my $row = $csv->getline ($fh)) {
            # do something with @$row
            }
        close $fh or die "file.csv: $!";

       or

        my $aoa = csv (in => "file.csv", on_in => sub {
            # do something with %_
            });

       Reading only a single column

        my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
        open my $fh, "<", "file.csv" or die "file.csv: $!";
        # get only the 4th column
        my @column = map { $_->[3] } @{$csv->getline_all ($fh)};
        close $fh or die "file.csv: $!";

       with "csv", you could do

        my @column = map { $_->[0] }
            @{csv (in => "file.csv", fragment => "col=4")};

   Parsing CSV strings:
        my $csv = Text::CSV_XS->new ({ keep_meta_info => 1, binary => 1 });

        my $sample_input_string =
            qq{"I said, ""Hi!""",Yes,"",2.34,,"1.09","\x{20ac}",};
        if ($csv->parse ($sample_input_string)) {
            my @field = $csv->fields;
            foreach my $col (0 .. $#field) {
                my $quo = $csv->is_quoted ($col) ? $csv->{quote_char} : "";
                printf "%2d: %s%s%s\n", $col, $quo, $field[$col], $quo;
                }
            }
        else {
            print STDERR "parse () failed on argument: ",
                $csv->error_input, "\n";
            $csv->error_diag ();
            }

       Parsing CSV from memory

       Given a complete CSV data-set in scalar $data,  generate a list of lists to represent the
       rows and fields

        # The data
        my $data = join "\r\n" => map { join "," => 0 .. 5 } 0 .. 5;

        # in a loop
        my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
        open my $fh, "<", \$data;
        my @foo;
        while (my $row = $csv->getline ($fh)) {
            push @foo, $row;
            }
        close $fh;

        # a single call
        my $foo = csv (in => \$data);

   Printing CSV data
       The fast way: using "print"

       An example for creating "CSV" files using the "print" method:

        my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
        open my $fh, ">", "foo.csv" or die "foo.csv: $!";
        for (1 .. 10) {
            $csv->print ($fh, [ $_, "$_" ]) or $csv->error_diag;
            }
        close $fh or die "$tbl.csv: $!";

       The slow way: using "combine" and "string"

       or using the slower "combine" and "string" methods:

        my $csv = Text::CSV_XS->new;

        open my $csv_fh, ">", "hello.csv" or die "hello.csv: $!";

        my @sample_input_fields = (
            'You said, "Hello!"',   5.67,
            '"Surely"',   '',   '3.14159');
        if ($csv->combine (@sample_input_fields)) {
            print $csv_fh $csv->string, "\n";
            }
        else {
            print "combine () failed on argument: ",
                $csv->error_input, "\n";
            }
        close $csv_fh or die "hello.csv: $!";

       Generating CSV into memory

       Format a data-set (@foo) into a scalar value in memory ($data):

        # The data
        my @foo = map { [ 0 .. 5 ] } 0 .. 3;

        # in a loop
        my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1, eol => "\r\n" });
        open my $fh, ">", \my $data;
        $csv->print ($fh, $_) for @foo;
        close $fh;

        # a single call
        csv (in => \@foo, out => \my $data);

   Rewriting CSV
       Rewrite "CSV" files with ";" as separator character to well-formed "CSV":

        use Text::CSV_XS qw( csv );
        csv (in => csv (in => "bad.csv", sep_char => ";"), out => *STDOUT);

       As "STDOUT" is now default in "csv", a one-liner converting a UTF-16 CSV file with BOM and
       TAB-separation to valid UTF-8 CSV could be:

        $ perl -C3 -MText::CSV_XS=csv -we\
           'csv(in=>"utf16tab.csv",encoding=>"utf16",sep=>"\t")' >utf8.csv

   Dumping database tables to CSV
       Dumping a database table can be simple as this (TIMTOWTDI):

        my $dbh = DBI->connect (...);
        my $sql = "select * from foo";

        # using your own loop
        open my $fh, ">", "foo.csv" or die "foo.csv: $!\n";
        my $csv = Text::CSV_XS->new ({ binary => 1, eol => "\r\n" });
        my $sth = $dbh->prepare ($sql); $sth->execute;
        $csv->print ($fh, $sth->{NAME_lc});
        while (my $row = $sth->fetch) {
            $csv->print ($fh, $row);
            }

        # using the csv function, all in memory
        csv (out => "foo.csv", in => $dbh->selectall_arrayref ($sql));

        # using the csv function, streaming with callbacks
        my $sth = $dbh->prepare ($sql); $sth->execute;
        csv (out => "foo.csv", in => sub { $sth->fetch            });
        csv (out => "foo.csv", in => sub { $sth->fetchrow_hashref });

       Note that this does not discriminate between "empty" values and NULL-values from the
       database,  as both will be the same empty field in CSV.  To enable distinction between the
       two, use "quote_empty".

        csv (out => "foo.csv", in => sub { $sth->fetch }, quote_empty => 1);

       If the database import utility supports special sequences to insert "NULL" values into the
       database,  like MySQL/MariaDB supports "\N",  use a filter or a map

        csv (out => "foo.csv", in => sub { $sth->fetch },
                            on_in => sub { $_ //= "\\N" for @{$_[1]} });

        while (my $row = $sth->fetch) {
            $csv->print ($fh, [ map { $_ // "\\N" } @$row ]);
            }

       Note that this will not work as expected when choosing the backslash ("\") as
       "escape_char", as that will cause the "\" to need to be escaped by yet another "\",  which
       will cause the field to need quotation and thus ending up as "\\N" instead of "\N". See
       also "undef_str".

        csv (out => "foo.csv", in => sub { $sth->fetch }, undef_str => "\\N");

       These special sequences are not recognized by  Text::CSV_XS  on parsing the CSV generated
       like this, but map and filter are your friends again

        while (my $row = $csv->getline ($fh)) {
            $sth->execute (map { $_ eq "\\N" ? undef : $_ } @$row);
            }

        csv (in => "foo.csv", filter => { 1 => sub {
            $sth->execute (map { $_ eq "\\N" ? undef : $_ } @{$_[1]}); 0; }});

   Converting CSV to JSON
        use Text::CSV_XS qw( csv );
        use JSON; # or Cpanel::JSON::XS for better performance

        # AoA (no header interpretation)
        say encode_json (csv (in => "file.csv"));

        # AoH (convert to structures)
        say encode_json (csv (in => "file.csv", bom => 1));

       Yes, it is that simple.

   The examples folder
       For more extended examples, see the examples/ 1. sub-directory in the original
       distribution or the git repository 2.

        1. https://github.com/Tux/Text-CSV_XS/tree/master/examples
        2. https://github.com/Tux/Text-CSV_XS

       The following files can be found there:

       parser-xs.pl
         This can be used as a boilerplate to parse invalid "CSV"  and parse beyond (expected)
         errors alternative to using the "error" callback.

          $ perl examples/parser-xs.pl bad.csv >good.csv

       csv-check
         This is a command-line tool that uses parser-xs.pl  techniques to check the "CSV" file
         and report on its content.

          $ csv-check files/utf8.csv
          Checked files/utf8.csv  with csv-check 1.9
          using Text::CSV_XS 1.32 with perl 5.26.0 and Unicode 9.0.0
          OK: rows: 1, columns: 2
              sep = <,>, quo = <">, bin = <1>, eol = <"\n">

       csv-split
         This command splits "CSV" files into smaller files,  keeping (part of) the header.
         Options include maximum number of (data) rows per file and maximum number of columns per
         file or a combination of the two.

       csv2xls
         A script to convert "CSV" to Microsoft Excel ("XLS"). This requires extra modules
         Date::Calc and Spreadsheet::WriteExcel. The converter accepts various options and can
         produce UTF-8 compliant Excel files.

       csv2xlsx
         A script to convert "CSV" to Microsoft Excel ("XLSX").  This requires the modules
         Date::Calc and Spreadsheet::Writer::XLSX.  The converter does accept various options
         including merging several "CSV" files into a single Excel file.

       csvdiff
         A script that provides colorized diff on sorted CSV files,  assuming  first line is
         header and first field is the key. Output options include colorized ANSI escape codes or
         HTML.

          $ csvdiff --html --output=diff.html file1.csv file2.csv

       rewrite.pl
         A script to rewrite (in)valid CSV into valid CSV files.  Script has options to generate
         confusing CSV files or CSV files that conform to Dutch MS-Excel exports (using ";" as
         separation).

         Script - by default - honors BOM  and auto-detects separation converting it to default
         standard CSV with "," as separator.

CAVEATS
       Text::CSV_XS  is not designed to detect the characters used to quote and separate fields.
       The parsing is done using predefined  (default) settings.  In the examples  sub-directory,
       you can find scripts  that demonstrate how you could try to detect these characters
       yourself.

   Microsoft Excel
       The import/export from Microsoft Excel is a risky task, according to the documentation in
       "Text::CSV::Separator".  Microsoft uses the system's list separator defined in the
       regional settings, which happens to be a semicolon for Dutch, German and Spanish (and
       probably some others as well).   For the English locale,  the default is a comma.   In
       Windows however,  the user is free to choose a  predefined locale,  and then change  every
       individual setting in it, so checking the locale is no solution.

       As of version 1.17, a lone first line with just

         sep=;

       will be recognized and honored when parsing with "getline".

TODO
       More Errors & Warnings
         New extensions ought to be  clear and concise  in reporting what  error has occurred
         where and why, and maybe also offer a remedy to the problem.

         "error_diag" is a (very) good start, but there is more work to be done in this area.

         Basic calls  should croak or warn on  illegal parameters.  Errors should be documented.

       setting meta info
         Future extensions might include extending the "meta_info", "is_quoted", and  "is_binary"
         to accept setting these  flags for  fields,  so you can specify which fields are quoted
         in the "combine"/"string" combination.

          $csv->meta_info (0, 1, 1, 3, 0, 0);
          $csv->is_quoted (3, 1);

         Metadata Vocabulary for Tabular Data <http://w3c.github.io/csvw/metadata/> (a W3C
         editor's draft) could be an example for supporting more metadata.

       Parse the whole file at once
         Implement new methods or functions  that enable parsing of a  complete file at once,
         returning a list of hashes. Possible extension to this could be to enable a column
         selection on the call:

          my @AoH = $csv->parse_file ($filename, { cols => [ 1, 4..8, 12 ]});

         returning something like

          [ { fields => [ 1, 2, "foo", 4.5, undef, "", 8 ],
              flags  => [ ... ],
              },
            { fields => [ ... ],
              .
              },
            ]

         Note that the "csv" function already supports most of this,  but does not return flags.
         "getline_all" returns all rows for an open stream, but this will not return flags
         either.  "fragment"  can reduce the  required  rows or columns, but cannot combine them.

       Cookbook
         Write a document that has recipes for  most known  non-standard  (and maybe some
         standard)  "CSV" formats,  including formats that use  "TAB",  ";", "|", or other non-
         comma separators.

         Examples could be taken from W3C's CSV on the Web: Use Cases and Requirements
         <http://w3c.github.io/csvw/use-cases-and-requirements/index.html>

       Steal
         Steal good new ideas and features from PapaParse <http://papaparse.com> or csvkit
         <http://csvkit.readthedocs.org>.

       Raku support
         Raku support can be found here <https://github.com/Tux/CSV>. The interface is richer in
         support than the Perl5 API, as Raku supports more types.

         The Raku version does not (yet) support pure binary CSV datasets.

   NOT TODO
       combined methods
         Requests for adding means (methods) that combine "combine" and "string" in a single call
         will not be honored (use "print" instead).   Likewise for "parse" and "fields"  (use
         "getline" instead), given the problems with embedded newlines.

   Release plan
       No guarantees, but this is what I had in mind some time ago:

       o DIAGNOSTICS section in pod to *describe* the errors (see below)

EBCDIC
       Everything should now work on native EBCDIC systems.   As the test does not cover all
       possible codepoints and Encode does not support "utf-ebcdic", there is no guarantee that
       all handling of Unicode is done correct.

       Opening "EBCDIC" encoded files on  "ASCII"+  systems is likely to succeed using Encode's
       "cp37", "cp1047", or "posix-bc":

        open my $fh, "<:encoding(cp1047)", "ebcdic_file.csv" or die "...";

DIAGNOSTICS
       Still under construction ...

       If an error occurs,  "$csv->error_diag" can be used to get information on the cause of the
       failure. Note that for speed reasons the internal value is never cleared on success,  so
       using the value returned by "error_diag" in normal cases - when no error occurred - may
       cause unexpected results.

       If the constructor failed, the cause can be found using "error_diag" as a class method,
       like "Text::CSV_XS->error_diag".

       The "$csv->error_diag" method is automatically invoked upon error when the contractor was
       called with  "auto_diag"  set to  1 or 2, or when autodie is in effect.  When set to 1,
       this will cause a "warn" with the error message,  when set to 2, it will "die". "2012 -
       EOF" is excluded from "auto_diag" reports.

       Errors can be (individually) caught using the "error" callback.

       The errors as described below are available. I have tried to make the error itself
       explanatory enough, but more descriptions will be added. For most of these errors, the
       first three capitals describe the error category:

       o INI

         Initialization error or option conflict.

       o ECR

         Carriage-Return related parse error.

       o EOF

         End-Of-File related parse error.

       o EIQ

         Parse error inside quotation.

       o EIF

         Parse error inside field.

       o ECB

         Combine error.

       o EHR

         HashRef parse related error.

       And below should be the complete list of error codes that can be returned:

       o 1001 "INI - sep_char is equal to quote_char or escape_char"

         The  separation character  cannot be equal to  the quotation character or to the escape
         character,  as this would invalidate all parsing rules.

       o 1002 "INI - allow_whitespace with escape_char or quote_char SP or TAB"

         Using the  "allow_whitespace"  attribute  when either "quote_char" or "escape_char"  is
         equal to "SPACE" or "TAB" is too ambiguous to allow.

       o 1003 "INI - \r or \n in main attr not allowed"

         Using default "eol" characters in either "sep_char", "quote_char",   or  "escape_char"
         is  not allowed.

       o 1004 "INI - callbacks should be undef or a hashref"

         The "callbacks"  attribute only allows one to be "undef" or a hash reference.

       o 1005 "INI - EOL too long"

         The value passed for EOL is exceeding its maximum length (16).

       o 1006 "INI - SEP too long"

         The value passed for SEP is exceeding its maximum length (16).

       o 1007 "INI - QUOTE too long"

         The value passed for QUOTE is exceeding its maximum length (16).

       o 1008 "INI - SEP undefined"

         The value passed for SEP should be defined and not empty.

       o 1010 "INI - the header is empty"

         The header line parsed in the "header" is empty.

       o 1011 "INI - the header contains more than one valid separator"

         The header line parsed in the  "header"  contains more than one  (unique) separator
         character out of the allowed set of separators.

       o 1012 "INI - the header contains an empty field"

         The header line parsed in the "header" contains an empty field.

       o 1013 "INI - the header contains nun-unique fields"

         The header line parsed in the  "header"  contains at least  two identical fields.

       o 1014 "INI - header called on undefined stream"

         The header line cannot be parsed from an undefined source.

       o 1500 "PRM - Invalid/unsupported argument(s)"

         Function or method called with invalid argument(s) or parameter(s).

       o 1501 "PRM - The key attribute is passed as an unsupported type"

         The "key" attribute is of an unsupported type.

       o 1502 "PRM - The value attribute is passed without the key attribute"

         The "value" attribute is only allowed when a valid key is given.

       o 1503 "PRM - The value attribute is passed as an unsupported type"

         The "value" attribute is of an unsupported type.

       o 2010 "ECR - QUO char inside quotes followed by CR not part of EOL"

         When  "eol"  has  been  set  to  anything  but the  default,  like "\r\t\n",  and  the
         "\r"  is  following  the   second   (closing) "quote_char", where the characters
         following the "\r" do not make up the "eol" sequence, this is an error.

       o 2011 "ECR - Characters after end of quoted field"

         Sequences like "1,foo,"bar"baz,22,1" are not allowed. "bar" is a quoted field and after
         the closing double-quote, there should be either a new-line sequence or a separation
         character.

       o 2012 "EOF - End of data in parsing input stream"

         Self-explaining. End-of-file while inside parsing a stream. Can happen only when reading
         from streams with "getline",  as using  "parse" is done on strings that are not required
         to have a trailing "eol".

       o 2013 "INI - Specification error for fragments RFC7111"

         Invalid specification for URI "fragment" specification.

       o 2014 "ENF - Inconsistent number of fields"

         Inconsistent number of fields under strict parsing.

       o 2021 "EIQ - NL char inside quotes, binary off"

         Sequences like "1,"foo\nbar",22,1" are allowed only when the binary option has been
         selected with the constructor.

       o 2022 "EIQ - CR char inside quotes, binary off"

         Sequences like "1,"foo\rbar",22,1" are allowed only when the binary option has been
         selected with the constructor.

       o 2023 "EIQ - QUO character not allowed"

         Sequences like ""foo "bar" baz",qu" and "2023,",2008-04-05,"Foo, Bar",\n" will cause
         this error.

       o 2024 "EIQ - EOF cannot be escaped, not even inside quotes"

         The escape character is not allowed as last character in an input stream.

       o 2025 "EIQ - Loose unescaped escape"

         An escape character should escape only characters that need escaping.

         Allowing  the escape  for other characters  is possible  with the attribute
         "allow_loose_escapes".

       o 2026 "EIQ - Binary character inside quoted field, binary off"

         Binary characters are not allowed by default.    Exceptions are fields that contain
         valid UTF-8,  that will automatically be upgraded if the content is valid UTF-8. Set
         "binary" to 1 to accept binary data.

       o 2027 "EIQ - Quoted field not terminated"

         When parsing a field that started with a quotation character,  the field is expected to
         be closed with a quotation character.   When the parsed line is exhausted before the
         quote is found, that field is not terminated.

       o 2030 "EIF - NL char inside unquoted verbatim, binary off"

       o 2031 "EIF - CR char is first char of field, not part of EOL"

       o 2032 "EIF - CR char inside unquoted, not part of EOL"

       o 2034 "EIF - Loose unescaped quote"

       o 2035 "EIF - Escaped EOF in unquoted field"

       o 2036 "EIF - ESC error"

       o 2037 "EIF - Binary character in unquoted field, binary off"

       o 2110 "ECB - Binary character in Combine, binary off"

       o 2200 "EIO - print to IO failed. See errno"

       o 3001 "EHR - Unsupported syntax for column_names ()"

       o 3002 "EHR - getline_hr () called before column_names ()"

       o 3003 "EHR - bind_columns () and column_names () fields count mismatch"

       o 3004 "EHR - bind_columns () only accepts refs to scalars"

       o 3006 "EHR - bind_columns () did not pass enough refs for parsed fields"

       o 3007 "EHR - bind_columns needs refs to writable scalars"

       o 3008 "EHR - unexpected error in bound fields"

       o 3009 "EHR - print_hr () called before column_names ()"

       o 3010 "EHR - print_hr () called with invalid arguments"

SEE ALSO
       IO::File,  IO::Handle,  IO::Wrap,  Text::CSV,  Text::CSV_PP, Text::CSV::Encoded,
       Text::CSV::Separator,    Text::CSV::Slurp, Spreadsheet::CSV and Spreadsheet::Read, and of
       course perl.

       If you are using Raku,  have a look at "Text::CSV" in the Raku ecosystem, offering the
       same features.

       non-perl

       A CSV parser in JavaScript,  also used by W3C <http://www.w3.org>,  is the multi-threaded
       in-browser PapaParse <http://papaparse.com/>.

       csvkit <http://csvkit.readthedocs.org> is a python CSV parsing toolkit.

AUTHOR
       Alan Citterman <alan AT mfgrtl.com> wrote the original Perl module.  Please don't send mail
       concerning Text::CSV_XS to Alan, who is not involved in the C/XS part that is now the main
       part of the module.

       Jochen Wiedmann <joe AT ispsoft.de> rewrote the en- and decoding in C by implementing a
       simple finite-state machine.   He added variable quote, escape and separator characters,
       the binary mode and the print and getline methods. See ChangeLog releases 0.10 through
       0.23.

       H.Merijn Brand <h.m.brand AT xs4all.nl> cleaned up the code,  added the field flags methods,
       wrote the major part of the test suite, completed the documentation,   fixed most RT bugs,
       added all the allow flags and the "csv" function. See ChangeLog releases 0.25 and on.

COPYRIGHT AND LICENSE
        Copyright (C) 2007-2021 H.Merijn Brand.  All rights reserved.
        Copyright (C) 1998-2001 Jochen Wiedmann. All rights reserved.
        Copyright (C) 1997      Alan Citterman.  All rights reserved.

       This library is free software;  you can redistribute and/or modify it under the same terms
       as Perl itself.

perl v5.34.0                                2022-02-06                                CSV_XS(3pm)

Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2024-12-07 19:30 @18.97.9.168 CrawledBy CCBot/2.0 (https://commoncrawl.org/faq/)
Valid XHTML 1.0!Valid CSS!