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run code in 300+ PHP versions simultaneously
<?php $a = array(100=>'a',200=>'b',300=>'c',400=>'d'); array_unshift($a,'z'); print_R($a); // What you have to do $a = array(100=>'a',200=>'b',300=>'c',400=>'d'); $a = array(0=>'z') + $a; print_R($a);

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81.33 ms | 402 KiB | 5 Q