如何在php中将字符串转换为数组

$str = "Hello,World,Hi";
$arr = explode(',', $str);
print_r($arr);

Array
(
    [0] => Hello
    [1] => World
    [2] => Hi
)

$str = "Hello,World,Hi";
$arr = preg_split('/[,]/', $str);
print_r($arr);

Array
(
    [0] => Hello
    [1] => World
    [2] => Hi
)

$str = "Hello,World,Hi";
$arr = str_split($str, 5);
print_r($arr);

Array
(
    [0] => Hello
    [1] => ,Worl
    [2] => d,Hi
)

$str = "Hello,World,Hi";
$arr = str_split($str, strlen($str));
print_r($arr);

Array
(
    [0] => Hello,World,Hi
)

$str = '{"name":"John","age":30,"city":"New York"}';
$arr = json_decode($str, true);
print_r($arr);

Array
(
    [name] => John
    [age] => 30
    [city] => New York
)

$str = "name=John&age=30&city=New+York";
parse_str($str, $arr);
print_r($arr);

Array
(
    [name] => John
    [age] => 30
    [city] => New York
)