Returns all of haystack starting from and including the first
   occurrence of needle to the end.
  
haystackThe string to search in
needle
       If needle is not a string, it is converted to
       an integer and applied as the ordinal value of a character.
      
before_needle
       If TRUE, stristr()
       returns the part of the haystack before the
       first occurrence of the needle (excluding needle).
      
   needle and haystack
   are examined in a case-insensitive manner.
  
   Returns the matched substring. If needle is not
   found, returns FALSE.
  
| Version | Description | 
|---|---|
| 5.3.0 | Added the optional parameter before_needle. | 
| 4.3.0 | stristr() was made binary safe. | 
Example #1 stristr() example
<?php
  $email = 'USER@EXAMPLE.com';
  echo stristr($email, 'e'); // outputs ER@EXAMPLE.com
  echo stristr($email, 'e', true); // As of PHP 5.3.0, outputs US
?>
Example #2 Testing if a string is found or not
<?php
  $string = 'Hello World!';
  if(stristr($string, 'earth') === FALSE) {
    echo '"earth" not found in string';
  }
// outputs: "earth" not found in string
?>
Example #3 Using a non "string" needle
<?php
  $string = 'APPLE';
  echo stristr($string, 97); // 97 = lowercase a
// outputs: APPLE
?>
Note: This function is binary-safe.