PHP5.4 json_decode生成格式错误的json

<?php
$jsonString = '{"name":"John", "age":30, "city":"New York"}';

// 解码为PHP对象
$object = json_decode($jsonString);
if ($object === null && json_last_error() !== JSON_ERROR_NONE) {
    echo "JSON解码错误: " . json_last_error_msg();
} else {
    echo "解码成功: ";
    print_r($object);
}

// 解码为PHP数组
$array = json_decode($jsonString, true);
if ($array === null && json_last_error() !== JSON_ERROR_NONE) {
    echo "JSON解码错误: " . json_last_error_msg();
} else {
    echo "解码成功: ";
    print_r($array);
}
?>

$jsonString = json_encode($rawString, JSON_UNESCAPED_UNICODE);
$decodedObject = json_decode($jsonString);