3v4l.org

run code in 300+ PHP versions simultaneously
<?php echo preg_replace_callback('/\b[^\s]*a\b/i', fn($matches) => str_replace("a", "o", $matches[0]), 'kak kaka aaak aaa');
Output for 8.0.1 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
kak koko aaak ooo

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77.52 ms | 406 KiB | 5 Q