Common ways to traverse php arrays

1. One-dimensional array traversal

foreach($array as $value){
	echo $value;
}

2. Two-dimensional array traversal

foreach($array $key=>$val){
	echo $key.'=>'.$val;
}

3. Multi-dimensional array traversal

public static function multi_arr_foreach($arr) {
    static $data; 
    if (!is_array ($arr)) {
        return $data;
    }
    foreach ($arr as $key => $val ) {
        if (is_array ($val)) {
            self::multi_arr_foreach($val);
        } else {
            $data[]=$val;
        }
    }
    return $data;
}

But I saw a very short way of writing it, and I don’t quite understand it yet

function loop_array($arr){
$value = is_array($arr) ? array_map('loop_array',$arr) : $arr;
return $value;
}

The above introduces the common methods of PHP array traversal, including aspects of content. I hope it will be helpful to friends who are interested in PHP tutorials.