3v4l.org

run code in 300+ PHP versions simultaneously
<?php $str = "4444,4444,5555,5555,4444,4444"; if(preg_match("/^\d{4}(,\d{4})*$/",$str)){ echo "it matched"; } else { echo "no match"; }

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31.94 ms | 402 KiB | 5 Q