<?php  

$jsonString = '{"message":"Hello, World!"}';  

$jsonObject = json_decode($jsonString);  

// 修改JSON对象  

$jsonObject->message = "Goodbye, World!";  

// 将修改后的对象转换回JSON字符串  

$newJsonString = json_encode($jsonObject);  

echo $newJsonString; // 输出: {"message":"Goodbye, World!"}  

?>

<?php  

$string = "He said, \"Hello, World!\"";  

$json = json_encode(array("message" => $string));  

echo $json; // 输出: {"message":"He said, \"Hello, World!\""}  

?>