如何將數組轉換成鍵值對字符串

function array2string($array){ $string = []; if($array && is_array($array)){ foreach ($array as $key=> $value){ $string[] = $key.'->'.$value; } } return implode(',',$string); } $array1= array('a', 'b', 'c', 'd'); echo $a = array2string($array1);