(PHP 3 >= 3.0.6, PHP 4, PHP 5)
stristr -- 
     Case-insensitive 
strstr()
    Description
string 
stristr ( string haystack, string needle )
     Returns all of haystack from the first
     occurrence of needle to the end.
     needle and haystack
     are examined in a case-insensitive manner.
    
     If needle is not found, returns FALSE.
    
     If needle is not a string, it is converted
     to an integer and applied as the ordinal value of a character.
    
     
Example 1. stristr() example 
<?php   $email = 'USER@EXAMPLE.com';   echo stristr($email, 'e'); // outputs ER@EXAMPLE.com ?>
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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 ?>
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Example 3. Using a non "string" needle 
<?php   $string = 'APPLE';   echo stristr($string, 97); // 97 = lowercase a // outputs: APPLE ?>
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    Note: This function is
binary-safe.
     See also 
     strstr(),
     strrchr(), 
     substr(), and
     ereg().