3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = array( 'a'=>1, 'b'=>2, 'c'=>3 ); $b = array( 'b'=>3, 'c'=>4, 'd'=>5 ); foreach(array_keys($a + $b) as $key){ echo $key; }

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38.15 ms | 402 KiB | 5 Q