[C#][php] POST json data TO a PHP page

原本只是很簡單的，跨頁傳值從C#到php
沒想到搞了半天，php那端一直接收不到json值

string json = "{\"user\":\"test\"," +

                "\"n\":\"2\"}";

var webAddr = "http://";

var httpWebRequest = (HttpWebRequest)WebRequest.Create(webAddr);

httpWebRequest.Method = "POST";

httpWebRequest.ContentType = "application/json";

httpWebRequest.ContentLength = json.Length;

using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))

{

     streamWriter.Write(json);

     streamWriter.Close();

}

var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();

using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))

{

     var result = streamReader.ReadToEnd();

     //return result;

}

找了很久，原來是php那端看不懂，C#這邊傳過去的json格式
在php接收那端需加上

// Error handling is left as an exercise
$input = json_decode(file_get_contents('php://input'), true);

這樣就行了，然後這是php端的改法
C#端也有另一種寫法

string postData = "user=" + HttpUtility.UrlEncode("test") +

                  "&n=" + HttpUtility.UrlEncode("2");

byte[] byteArray = Encoding.ASCII.GetBytes(postData);

string postData = "json=" +
                HttpUtility.UrlEncode(serializer.Serialize(p));

php端：

$json_array = json_decode($_POST['json']);