php man page for substr_compare

SUBSTR_COMPARE(3)							 1							 SUBSTR_COMPARE(3)

substr_compare - Binary safe comparison of two strings from an offset, up to length characters

SYNOPSIS
       int substr_compare (string  $main_str, string  $str, int  $offset, [int	$length], [bool  $case_insensitivity = false])

DESCRIPTION
       substr_compare(3) compares $main_str from position $offset with $str up to $length characters.

PARAMETERS
	      o $main_str
		- The main string being compared.

	      o $str
		- The secondary string being compared.

	      o $offset
		- The start position for the comparison. If negative, it starts counting from the end of the string.

	      o $length
		-  The	length	of  the comparison. The default value is the largest of the length of the $str compared to the length of $main_str
		less the $offset.

	      o $case_insensitivity
		- If $case_insensitivity is TRUE, comparison is case insensitive.

RETURN VALUES
	Returns < 0 if $main_str from position $offset is less than $str, > 0 if it is greater than $str, and 0 if they are equal. If  $offset	is
       equal  to  or greater than the length of $main_str, or the $length is set and is less than 1 (prior to PHP 5.6), substr_compare(3) prints a
       warning and returns FALSE.

CHANGELOG
       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.6.0	|						    |
       |	|						    |
       |	|		$length may now be 0.		    |
       |	|						    |
       | 5.1.0	|						    |
       |	|						    |
       |	|  Added the possibility to use a negative $offset. |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES
       Example #1

	      A substr_compare(3) example

	      <?php
	      echo substr_compare("abcde", "bc", 1, 2); // 0
	      echo substr_compare("abcde", "de", -2, 2); // 0
	      echo substr_compare("abcde", "bcg", 1, 2); // 0
	      echo substr_compare("abcde", "BC", 1, 2, true); // 0
	      echo substr_compare("abcde", "bc", 1, 3); // 1
	      echo substr_compare("abcde", "cd", 1, 2); // -1
	      echo substr_compare("abcde", "abc", 5, 1); // warning
	      ?>

SEE ALSO
       strncmp(3).

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