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run code in 300+ PHP versions simultaneously
<?php $a = "abab"; preg_replace("/(a)/", "$1-", $a); echo $a;
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
abab

preferences:
154.39 ms | 403 KiB | 214 Q