PHP stristr() Function: Usage, Parameters, Return Values, and Examples
This article explains PHP's case‑insensitive stristr() function, detailing its parameters, return behavior, and providing three practical code examples that demonstrate extracting substrings, checking for needle existence, and using integer needles.
The stristr() function in PHP finds the first occurrence of a substring in a string, performing a case‑insensitive search.
Parameters :
haystack : the string to search in.
needle : the substring to look for; if not a string it is converted to an integer character code.
before_needle (optional, boolean): when true, returns the part of haystack before the found needle (excluding the needle).
Return value : the matched portion of the string starting from the first occurrence of needle to the end of haystack. If the needle is not found, the function returns FALSE.
Example 1 – case‑insensitive extraction:
<?php
$email = '[email protected]';
echo stristr($email, 'e'); // outputs [email protected]
echo stristr($email, 'e', true); // outputs US (PHP 5.3.0+)
?>Example 2 – checking existence:
<?php
$string = 'Hello World!';
if (stristr($string, 'earth') === FALSE) {
echo "\"earth\" not found in string";
}
?>Example 3 – using an integer as needle (ASCII code for 'a'):
<?php
$string = 'APPLE';
echo stristr($string, 97); // outputs APPLE because 97 = 'a'
?>Signed-in readers can open the original source through BestHub's protected redirect.
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