3v4l.org

run code in 300+ PHP versions simultaneously
<?php $data = array( 1 => 0, 2 => 0, 3 => 1, 7 => 1, 4 => 3, 5 => 4, 6 => 5, 8 => 5 ); print_r( array_keys($data, 1) );

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30.89 ms | 402 KiB | 5 Q