Silent Optimisation Of Variables
<?php
$a;
// crii crii
3 || $b;
// ...
echo $c;
// warning: undefined variable $c;
?>
See PHP optimisation in action: undefined variables are only reported when they are used (sic).
The first one is omitted : there are no operation with it.
The second one is skipped: no need to execute 2nd term when the first one is already true.
The third one is reporting a warning, as expected.
See Also
- Silent PHP Optimisation [Try me]
PHP Error Messages
PHP Features
Last updated: 10 September 2026