php man page for strpos

STRPOS(3)								 1								 STRPOS(3)

strpos - Find the position of the first occurrence of a substring in a string

SYNOPSIS
       mixed strpos (string  $haystack, mixed  $needle, [int  $offset])

DESCRIPTION
	Find the numeric position of the first occurrence of $needle in the $haystack string.

PARAMETERS
	      o $haystack
		- The string to search in.

	      o $needle
		- If $needle is not a string, it is converted to an integer and applied as the ordinal value of a character.

	      o $offset
		- If specified, search will start this number of characters counted from the beginning of the string. Unlike strrpos(3) and strri-
		pos(3), the offset cannot be negative.

RETURN VALUES
	Returns the position of where the needle exists relative to the beginning of the $haystack string (independent of offset). Also note  that
       string positions start at 0, and not 1.

	Returns FALSE if the needle was not found.

       Warning

	      This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE. Please read the section on
	      Booleans for more information. Use the === operator for testing the return value of this function.

EXAMPLES
       Example #1

	      Using ===

	      <?php
	      $mystring = 'abc';
	      $findme	= 'a';
	      $pos = strpos($mystring, $findme);

	      // Note our use of ===.  Simply == would not work as expected
	      // because the position of 'a' was the 0th (first) character.
	      if ($pos === false) {
		  echo "The string '$findme' was not found in the string '$mystring'";
	      } else {
		  echo "The string '$findme' was found in the string '$mystring'";
		  echo " and exists at position $pos";
	      }
	      ?>

       Example #2

	      Using !==

	      <?php
	      $mystring = 'abc';
	      $findme	= 'a';
	      $pos = strpos($mystring, $findme);

	      // The !== operator can also be used.  Using != would not work as expected
	      // because the position of 'a' is 0. The statement (0 != false) evaluates
	      // to false.
	      if ($pos !== false) {
		   echo "The string '$findme' was found in the string '$mystring'";
		       echo " and exists at position $pos";
	      } else {
		   echo "The string '$findme' was not found in the string '$mystring'";
	      }
	      ?>

       Example #3

	      Using an offset

	      <?php
	      // We can search for the character, ignoring anything before the offset
	      $newstring = 'abcdef abcdef';
	      $pos = strpos($newstring, 'a', 1); // $pos = 7, not 0
	      ?>

NOTES
       Note

	      This function is binary-safe.

SEE ALSO
       stripos(3), strrpos(3), strripos(3), strstr(3), strpbrk(3), substr(3), preg_match(3).

PHP Documentation Group 														 STRPOS(3)