3v4l.org

run code in 300+ PHP versions simultaneously
<?php function foo() { echo __FUNCTION__, "\n"; return 'key'; } echo "??=\n"; $array = []; $array[foo()] ??= 'default'; echo "\nrough equivalent\n"; $array = []; if (!isset($array[foo()])) { $array[foo()] = 'default'; }
Output for 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
??= foo rough equivalent foo foo
Output for 7.3.0 - 7.3.33
Parse error: syntax error, unexpected '=' in /in/ITSK6 on line 10
Process exited with code 255.
preferences:
144.31 ms | 407 KiB | 5 Q