3v4l.org

run code in 300+ PHP versions simultaneously
<?php $headers = array( 'User-Agent' => 'Mozilla', ); $headers = array_change_key_case($headers); // Convert all keys to lower $keyExists = array_key_exists('user-agent', $headers); var_dump($keyExists);
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 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
bool(true)
preferences:
107.22 ms | 408 KiB | 5 Q