isalpha - phpMan

ISALPHA(3)                 Linux Programmer’s Manual                ISALPHA(3)



NAME
       isalnum,  isalpha,  isascii,  isblank, iscntrl, isdigit, isgraph, islower, isprint,
       ispunct, isspace, isupper, isxdigit - character classification routines

SYNOPSIS
       #include <ctype.h>

       int isalnum(int c);
       int isalpha(int c);
       int isascii(int c);
       int isblank(int c);
       int iscntrl(int c);
       int isdigit(int c);
       int isgraph(int c);
       int islower(int c);
       int isprint(int c);
       int ispunct(int c);
       int isspace(int c);
       int isupper(int c);
       int isxdigit(int c);

DESCRIPTION
       These functions check whether c, which must have the value of an unsigned  char  or
       EOF, falls into a certain character class according to the current locale.

       isalnum()
              checks  for  an  alphanumeric  character; it is equivalent to (isalpha(c) ||
              isdigit(c)).

       isalpha()
              checks for an alphabetic character; in the standard "C" locale, it is equiv-
              alent  to  (isupper(c)  || islower(c)).  In some locales, there may be addi-
              tional characters for which isalpha() is  true--letters  which  are  neither
              upper case nor lower case.

       isascii()
              checks  whether  c  is  a 7-bit unsigned char value that fits into the ASCII
              character set.  This function is a BSD extension and is also an SVID  exten-
              sion.

       isblank()
              checks for a blank character; that is, a space or a tab.  This function is a
              GNU extension.

       iscntrl()
              checks for a control character.

       isdigit()
              checks for a digit (0 through 9).

       isgraph()
              checks for any printable character except space.

       islower()
              checks for a lower-case character.

       isprint()
              checks for any printable character including space.

       ispunct()
              checks for any printable character which is not a space or  an  alphanumeric
              character.

       isspace()
              checks  for  white-space  characters.  In the "C" and "POSIX" locales, these
              are: space, form-feed (â€â€™\fâ€â€™), newline (â€â€™\nâ€â€™), carriage return (â€â€™\râ€â€™),  hori-
              zontal tab (â€â€™\tâ€â€™), and vertical tab (â€â€™\vâ€â€™).

       isupper()
              checks for an uppercase letter.

       isxdigit()
              checks for a hexadecimal digits, i.e. one of 0 1 2 3 4 5 6 7 8 9 a b c d e f
              A B C D E F.

RETURN VALUE
       The values returned are nonzero if the character c falls into the tested class, and
       a zero value if not.

CONFORMING TO
       ANSI  -  C,  BSD  4.3.  isascii() is a BSD extension and is also an SVID extension.
       isblank() is a GNU extension.

NOTE
       The details of what characters belong  into  which  class  depend  on  the  current
       locale.   For  example,  isupper() will not recognize an A - umlaut as an uppercase
       letter in the default C locale.

SEE ALSO
       tolower(3), toupper(3), setlocale(3), ascii(7), locale(7)




GNU                               1995-09-02                        ISALPHA(3)

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