3v4l.org

run code in 300+ PHP versions simultaneously
<?php $foo = array( "a" => 1, "b" => 2, "c" => 3, "d" => 4, ); $foo = ['c' => $foo['c']] + $foo; var_export($foo); echo "\n---\n"; $bar = array( "a" => 1, "b" => 2, "d" => 4, ); if (array_key_exists('c', $bar)) { $bar = ['c' => $bar['c']] + $bar; } var_export($bar);
Output for 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
array ( 'c' => 3, 'a' => 1, 'b' => 2, 'd' => 4, ) --- array ( 'a' => 1, 'b' => 2, 'd' => 4, )
preferences:
141.85 ms | 407 KiB | 5 Q