stripos is slow because both input strings are always lowercased completely. This also entails unnecessary memory consumption.
preg_match with case-insensitive flag is a much faster alternative.
<?php
$haystack = str_repeat('A', 1e+7) . 'BBB';
$repetitions = 0;
$start = microtime(true);
do {
strpos($haystack, 'bbb');
$repetitions += 1;
} while (microtime(true) - $start < 5);
$rate = round($repetitions / (microtime(true) - $start));
$rate = str_pad($rate, 8, ' ', STR_PAD_LEFT);
print("strpos: $rate / second\n");
$repetitions = 0;
$start = microtime(true);
do {
stripos($haystack, 'bbb');
$repetitions += 1;
} while (microtime(true) - $start < 5);
$rate = round($repetitions / (microtime(true) - $start));
$rate = str_pad($rate, 8, ' ', STR_PAD_LEFT);
print("stripos: $rate / second\n");
$repetitions = 0;
$start = microtime(true);
do {
preg_match('/bbb/i', $haystack, $match, PREG_OFFSET_CAPTURE);
$repetitions += 1;
} while (microtime(true) - $start < 5);
$rate = round($repetitions / (microtime(true) - $start));
$rate = str_pad($rate, 8, ' ', STR_PAD_LEFT);
print("preg_match: $rate / second\n");strpos: 1192 / second
stripos: 176 / second
preg_match: 1118 / second
Description
stripos is slow because both input strings are always lowercased completely. This also entails unnecessary memory consumption.
preg_match with case-insensitive flag is a much faster alternative.
Source code:
php-src/ext/standard/string.c
Line 1914 in 9362d6f
Test case:
Example output:
PHP Version
PHP 8.0.14
Operating System
No response