PHP: Fastest way to handle undefined array key

Question

in a very tight loop I need to access tenthousands of values in an array containing millions of elements. The key can be undefinied: In that case it shall be legal to return

Answer 1

I prefer using the isset function instead of escaping the error. I made a function to check the key exists and if not returns a default value, in the case of nested arrays you just need to add the other keys in order:

Nested array lookup:

/**
 * Lookup array value.
 *
 * @param array $array
 * @param array $keys
 * @param $defaultValue
 */
public static function array_key_lookup($array, $keys, $defaultValue)
{
    $value = $array;
    foreach ($keys as $key) {
        if (isset($value[$key])) {
            $value = $value[$key];
        } else {
            $value = $defaultValue;
            break;
        }
    }

    return $value;
}

Usage example:

$array = [
    'key1' => 'value1',
    'key2' => 'value2',
    'key3' => [
        'key3a' => 'value3a',
        'key3b' => 'value3b'
    ]
];

array_key_lookup($array, ['key3', 'key3a'], 'default')
'value3a'

array_key_lookup($array, ['key2', 'key2a'], 'default')
'default'

array_key_lookup($array, ['key2'], 'default')
'value2'

array_key_lookup($array, ['key5'], 'default')
'default'

Escaping the error:

$value = @$array[$key1][$key2] ?: $defaultValue;