$jsonString = '{"name":"John", "age":30, "city":"New York"}';
$phpArray = json_decode($jsonString, true); // 转换为关联数组
$phpObject = json_decode($jsonString); // 转换为对象

// 访问属性
echo $phpArray['name']; // 输出: John
echo $phpObject->name;  // 输出: John

$jsonArray = '[{"name":"John"}, {"name":"Jane"}]';
$phpArray = json_decode($jsonArray, true);

foreach ($phpArray as $item) {
    echo $item['name'] . "\n";
}
// 输出:
// John
// Jane

$jsonNested = '{
    "users": [
        {"id":1, "name":"John"},
        {"id":2, "name":"Jane"}
    ],
    "status":"success"
}';

$data = json_decode($jsonNested, true);

echo $data['status']; // 输出: success
echo $data['users'][0]['name']; // 输出: John

$json = '{"name":"John", age:30}'; // 错误的JSON
$data = json_decode($json);

if (json_last_error() !== JSON_ERROR_NONE) {
    echo 'JSON解析错误: ' . json_last_error_msg();
}

$data = json_decode('{"name":"John"}', true);

if (isset($data['age'])) {
    echo $data['age'];
} else {
    echo 'age属性不存在';
}

$array = ['name' => '张三'];
$json = json_encode($array, JSON_UNESCAPED_UNICODE);