# phpman > perldoc > Dpkg::Version ## NAME [Dpkg::Version](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion/markdown) - handling and comparing dpkg-style version numbers ## DESCRIPTION The [Dpkg::Version](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion/markdown) module provides pure-Perl routines to compare dpkg-style version numbers (as used in Debian packages) and also an object oriented interface overriding perl operators to do the right thing when you compare [Dpkg::Version](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion/markdown) object between them. ## METHODS $v = [Dpkg::Version](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion/markdown)->new($version, %opts) Create a new [Dpkg::Version](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion/markdown) object corresponding to the version indicated in the string (scalar) $version. By default it will accepts any string and consider it as a valid version. If you pass the option "check => 1", it will return undef if the version is invalid (see version_check for details). You can always call $v->is_valid() later on to verify that the version is valid. boolean evaluation When the [Dpkg::Version](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion/markdown) object is used in a boolean evaluation (for example in "if ($v)" or "$v ? \"$v\" : 'default'") it returns true if the version stored is valid ($v->is_valid()) and false otherwise. Notice: Between dpkg 1.15.7.2 and 1.19.1 this overload used to return $v->as_string() if $v->is_valid(), a breaking change in behavior that caused "0" versions to be evaluated as false. To catch any possibly intended code that relied on those semantics, this overload will emit a warning with category "[Dpkg::Version::semantic_change::overload::bool](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion%3A%3Asemanticchange%3A%3Aoverload%3A%3Abool/markdown)" until dpkg 1.20.x. Once fixed, or for already valid code the warning can be quiesced with no if $[Dpkg::Version::VERSION](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion%3A%3AVERSION/markdown) ge '1.02', warnings => qw([Dpkg::Version::semantic_change::overload::bool](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion%3A%3Asemanticchange%3A%3Aoverload%3A%3Abool/markdown)); added after the "use [Dpkg::Version](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion/markdown)". $v->is_valid() Returns true if the version is valid, false otherwise. $v->epoch(), $v->version(), $v->revision() Returns the corresponding part of the full version string. $v->is_native() Returns true if the version is native, false if it has a revision. $v1 <=> $v2, $v1 < $v2, $v1 <= $v2, $v1 > $v2, $v1 >= $v2 Numerical comparison of various versions numbers. One of the two operands needs to be a [Dpkg::Version](https://www.chedong.com/phpMan.php/perldoc/Dpkg%3A%3AVersion/markdown), the other one can be anything provided that its string representation is a version number. "$v", $v->as_string(), $v->as_string(%options) Accepts an optional option hash reference, affecting the string conversion. Options: omit_epoch (defaults to 0) Omit the epoch, if present, in the output string. omit_revision (defaults to 0) Omit the revision, if present, in the output string. Returns the string representation of the version number. ## FUNCTIONS All the functions are exported by default. ### version_compare Returns -1 if $a is earlier than $b, 0 if they are equal and 1 if $a is later than $b. If $a or $b are not valid version numbers, it dies with an error. ### version_compare_relation Returns the result (0 or 1) of the given comparison operation. This function is implemented on top of version_compare(). Allowed values for $rel are the exported constants REL_GT, REL_GE, REL_EQ, REL_LE, REL_LT. Use version_normalize_relation() if you have an input string containing the operator. $rel = version_normalize_relation($rel_string) Returns the normalized constant of the relation $rel (a value among REL_GT, REL_GE, REL_EQ, REL_LE and REL_LT). Supported relations names in input are: "gt", "ge", "eq", "le", "lt", ">>", ">=", "=", "<=", "<<". ">" and "<" are also supported but should not be used as they are obsolete aliases of ">=" and "<=". ### version_compare_string String comparison function used for comparing non-numerical parts of version numbers. Returns -1 if $a is earlier than $b, 0 if they are equal and 1 if $a is later than $b. The "~" character always sort lower than anything else. Digits sort lower than non-digits. Among remaining characters alphabetic characters (A-Z, a-z) sort lower than the other ones. Within each range, the ASCII decimal value of the character is used to sort between characters. ### version_compare_part Compare two corresponding sub-parts of a version number (either upstream version or debian revision). Each parameter is split by version_split_digits() and resulting items are compared together. As soon as a difference happens, it returns -1 if $a is earlier than $b, 0 if they are equal and 1 if $a is later than $b. @items = version_split_digits($version) Splits a string in items that are each entirely composed either of digits or of non-digits. For instance for "1.024~beta1+svn234" it would return ("1", ".", "024", "~beta", "1", "+svn", "234"). ($ok, $msg) = version_check($version) $ok = version_check($version) Checks the validity of $version as a version number. Returns 1 in $ok if the version is valid, 0 otherwise. In the latter case, $msg contains a description of the problem with the $version scalar. ## CHANGES Version 1.03 (dpkg 1.20.0) Remove deprecation warning from semantic change in 1.02. Version 1.02 (dpkg 1.19.1) Semantic change: bool evaluation semantics restored to their original behavior. Version 1.01 (dpkg 1.17.0) New argument: Accept an options argument in $v->as_string(). New method: $v->is_native(). Version 1.00 (dpkg 1.15.6) Mark the module as public.