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 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.30, 8.2.0 - 8.2.26, 8.3.0 - 8.3.14, 8.4.1
bool(true)
preferences:
60.32 ms | 410 KiB | 5 Q