Online PHP editor | output for 0poR7

<?php $formData = array(); echo 'empty($formData[chain_id]): '; var_dump(empty($formData['chain_id'])); echo "\n"; echo '$formData[chain_id] === \'0\': '; var_dump($formData['chain_id'] === '0'); echo "\n"; $formData['chain_id'] = 0 echo 'empty($formData[chain_id]): '; var_dump(empty($formData['chain_id'])); echo "\n"; echo '$formData[chain_id] === \'0\': '; var_dump($formData['chain_id'] === '0'); echo "\n"; $formData['chain_id'] = 1 echo 'empty($formData[chain_id]): '; var_dump(empty($formData['chain_id'])); echo "\n"; echo '$formData[chain_id] === \'0\': '; var_dump($formData['chain_id'] === '0'); echo "\n";