PHP stristr() Function: Syntax, Parameters, Return Value, and Examples

stristr() is the case‑insensitive version of strstr() in PHP.

Signature:

string stristr ( string $haystack , mixed $needle [, bool $before_needle = false ] )

Description: Returns the portion of $haystack from the first occurrence of $needle to the end of the string, ignoring case. If $before_needle is true, the part before the needle is returned. If the needle is not found, FALSE is returned.

Parameters: $haystack – the string to search in. $needle – the string to search for; if not a string it is converted to an integer character code. $before_needle – optional boolean; when true, returns the segment before the needle (excluding the needle).

Return value: The matching substring, or FALSE if the needle is not found.

Example 1:

<?php
$email = '[email protected]';
echo stristr($email, 'e');          // Outputs [email protected]
echo stristr($email, 'e', true);   // Outputs US (since PHP 5.3.0)
?>

Example 2:

<?php
$string = 'Hello World!';
if (stristr($string, 'earth') === FALSE) {
    echo '"earth" not found in string';
}
?>

Example 3:

<?php
$string = 'APPLE';
echo stristr($string, 97); // 97 = ASCII for 'a', outputs APPLE
?>