array_key_first Gets the first key of an array &reftitle.description; mixedarray_key_first arrayarray Get the first key of the given array without affecting the internal array pointer. &reftitle.parameters; array An array. &reftitle.returnvalues; Returns the first key of array if the array is not empty; &null; otherwise. &reftitle.examples; 1, 'b' => 2, 'c' => 3]; $firstKey = array_key_first($array); var_dump($firstKey); ?> ]]> &example.outputs; &reftitle.notes; There are several ways to provide this functionality for versions prior to PHP 7.3.0. It is possible to use array_keys, but that may be rather inefficient. It is also possible to use reset and key, but that may change the internal array pointer. An efficient solution, which does not change the internal array pointer, written as polyfill: $unused) { return $key; } return NULL; } } ?> ]]> &reftitle.seealso; array_key_last reset