Master PHP’s stristr() for Case‑Insensitive String Searches

PHP’s stristr() function searches for the first occurrence of a substring within a string without regard to case.

Function Syntax

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

The function returns the portion of $haystack starting from the first match of $needle to the end of the string.

Parameters

haystack : The string to be searched.

needle : The substring to look for; if it is not a string it is cast to an integer representing a character code.

before_needle (optional): When set to true, the function returns the part of $haystack that appears before the first occurrence of $needle, excluding the needle itself.

Both $haystack and $needle are compared case‑insensitively.

Return Value

The function returns the matched portion of the string, or FALSE if the needle is not found.

Examples

Example 1 – Basic usage

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

Example 2 – Checking for absence

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

Example 3 – Using a character code

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

Note: Unlike strstr(), stristr() performs a case‑insensitive search.