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                                version_compare

   (PHP 4 >= 4.1.0)
   version_compare --  Compares two "PHP-standardized" version number
   strings

Description

   int 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 1 if the relationship is the one
   specified by the operator, 0 otherwise.

   Example 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");
   ?>
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