version_compare

Description

mixed version_compare ( string version1, string version2 [, string operator] )

version_compare() compares two "PHP-standardized" version number strings. This is useful if you would like to write programs working only on some versions of PHP.

version_compare() returns -1 if the first version is lower than the second, 0 if they are equal, and +1 if the second is lower.

The function first replaces _, - and + with a dot . in the version strings and also inserts dots . before and after any non number so that for example '4.3.2RC1' becomes '4.3.2.RC.1'. Then it splits the results like if you were using explode('.', $ver). Then it compares the parts starting from left to right. If a part contains special version strings these are handled in the following order: dev < alpha = a < beta = b < RC < pl. This way not only versions with different levels like '4.1' and '4.1.2' can be compared but also any PHP specific version containing development state.

If you specify the third optional operator argument, you can test for a particular relationship. The possible operators are: <, lt, <=, le, >, gt, >=, ge, ==, =, eq, !=, <>, ne respectively. Using this argument, the function will return TRUE if the relationship is the one specified by the operator, FALSE otherwise.

注: PHP_VERSION constant holds current PHP version.

例子 1. version_compare() example
<?php // prints -1 echo version_compare("4.0.4", "4.0.6"); // these all print 1 echo version_compare("4.0.4", "4.0.6", "<"); echo version_compare("4.0.6", "4.0.6", "eq"); ?>

add a note User Contributed Notes

arnoud at procurios dot nl
29-Sep-2004 05:28


If you're careful, this function actualy works quite nicely for comparing version numbers from programs other than PHP itself. I've used it to compare MySQL version numbers. The only issue is that version_compare doesn't recognize the 'gamma' addition that mysql uses as being later than 'alpha' or 'beta', because the latter two are treated specially. If you keep this in mind though, you should have no problems.

mina86 at tlen dot pl
01-Jul-2004 10:40


Here's a wrapper which is more tolerant as far as order of arguments is considered:



<?php

function ver_cmp($arg1, $arg2 = null, $arg3 = null) {

  static $phpversion = null;

  if ($phpversion===null) $phpversion = phpversion();



  switch (func_num_args()) {

  case 1: return version_compare($phpversion, $arg1);

  case 2:

    if (preg_match('/^[lg][te]|[<>]=?|[!=]?=|eq|ne|<>$/i', $arg1))

      return version_compare($phpversion, $arg2, $arg1);

    elseif (preg_match('/^[lg][te]|[<>]=?|[!=]?=|eq|ne|<>$/i', $arg2))

      return version_compare($phpversion, $arg1, $arg2);

    return version_compare($arg1, $arg2);

  default:

    $ver1 = $arg1;

    if (preg_match('/^[lg][te]|[<>]=?|[!=]?=|eq|ne|<>$/i', $arg2))

      return version_compare($arg1, $arg3, $arg2);

    return version_compare($arg1, $arg2, $arg3);

  }

}

?>



It also uses phpversion() as a default version if only one string is present. It can make your code look nicer 'cuz you can now write:

<?php if (ver_cmp($version1, '>=', $version2)) something; ?>

and to check a version string against the PHP's version you might use:

<?php if (ver_cmp('>=', $version)) something; ?>

instead of using phpversion().

aidan at php dot net
26-Jun-2004 06:02


This functionality is now implemented in the PEAR package PHP_Compat.



More information about using this function without upgrading your version of PHP can be found on the below link:



http://pear.php.net/package/PHP_Compat

eric at themepark dot com
22-Jun-2004 12:50


so in a nutshell... I believe it works best like this:





<?php


if (version_compare(php_version(), "4.3.0", ">=")) {


  // you're on 4.3.0 or later


} else {


  // you're not


}


?>

sam at wyvern dot non-spammers-remove dot com dot au
24-May-2004 02:18


Actually, it works to any degree:



<?php

version_compare('1.2.3.4RC7.7', '1.2.3.4RC7.8')

version_compare('8.2.50.4', '8.2.52.6')

?>



will both give -1 (ie the left is lower than the right).

add a note