array_find_key Returns the key of the first element satisfying a callback function &reftitle.description; mixedarray_find_key arrayarray callablecallback array_find_key returns the key of the first element of an &array; for which the given callback returns &true;. If no matching element is found the function returns &null;. &reftitle.parameters; array The &array; that should be searched. callback The callback function to call to check each element, which must be boolcallback mixedvalue mixedkey If this function returns &true;, the key is returned from array_find_key and the callback will not be called for further elements. &reftitle.returnvalues; The function returns the key of the first element for which the callback returns &true;. If no matching element is found the function returns &null;. &reftitle.examples; 'dog', 'b' => 'cat', 'c' => 'cow', 'd' => 'duck', 'e' => 'goose', 'f' => 'elephant' ]; // Find the first animal with a name longer than 4 characters. var_dump(array_find_key($array, function (string $value) { return strlen($value) > 4; })); // Find the first animal whose name begins with f. var_dump(array_find_key($array, function (string $value) { return str_starts_with($value, 'f'); })); // Find the first animal where the array key is the first symbol of the animal. var_dump(array_find_key($array, function (string $value, $key) { return $value[0] === $key; })); // Find the first animal where the array key matching a RegEx. var_dump(array_find_key($array, function ($value, $key) { return preg_match('/^([a-f])$/', $key); })); ?> ]]> &example.outputs; &reftitle.seealso; array_find array_all array_any array_filter array_reduce