array_keys()

array_keys() — Return all the keys or a subset of the keys of an array.

array_keys returns the keys, numeric and string, from the array.

If a filter_value is specified, then only the keys for that value are returned. Otherwise, all the keys from the array are returned.

Inputs: array: An array containing keys to return. filter_value: If specified, then only keys containing this value are returned. strict: Determines if strict comparison (===) should be used during the search.

Returns: Returns an array of all the keys in array.