爲什麼我們可以從作爲值傳遞給方法的參數獲取更新結果？

Question

在程序中，調用名爲HandleHttpRequest的方法，該方法接受HttpContext類的參數。

HandleHttpRequest處理httpContext.Request中的傳入請求並寫入對httpContext.Response的響應。

我的問題是爲什麼在撥打HandleHttpRequest完成後，程序可以獲得寫入httpContext.Response的響應？

是httpContext作爲值傳遞給HandleHttpRequest，而不是引用，是否正確？

謝謝。

HttpRequest httpRequest = new HttpRequest("", "http://localhost/my.ashx", "timestamp=20170216"); 
MemoryStream memoryStream = new MemoryStream(); 
TextWriter textWriter = new StreamWriter(memoryStream); 
HttpResponse httpResponse = new HttpResponse(textWriter); 
HttpContext httpContext = new HttpContext(httpRequest, httpResponse); 

HandleHttpRequest(httpContext); 

textWriter.Flush(); 
byte[] buffer = memoryStream.GetBuffer(); 

的HandleHttpRequest簽名是

public void HandleHttpRequest(HttpContext context) 

所以它的參數是不是一個參考。

Answer 1

將httpContext作爲值傳遞給HandleHttpRequest而不是引用，是否正確？

httpContext變量是對HttpContext的實例的引用。引用被傳遞給方法，所以方法返回後，方法所做的任何事情都會顯示出來。但請記住，引用變量是通過值傳遞給方法的，所以方法不能爲其分配另一個引用。

這裏是一個小應用程序，這將澄清一些混亂：

internal class Program { 

    private static void Main(string[] args) { 

     var p1 = new Person { Name = "George" }; 
     ChangeName(p1); 

     // This will have "George" because the method never operated 
     // on the person passed to it. 
     var name = p1.Name; 

     // Now we call this method which will change the name of the person 
     // we are passing to it. 
     ChangeName2(p1); 

     // Therefore, now it will have "Jerry" 
     var name2 = p1.Name; 

     var p2 = new Person { Name = "Kramer" }; 

     // Let's record this so we can compare it later 
     var p2Before = p2; 

     // Now we do the exact same thing we did when we passed by value, 
     // but now we pass by ref. 
     ChangeName(ref p2); 

     // This will have "Smith" 
     var name3 = p2.Name; 

     // This will return false; 
     var samePerson = p2 == p2Before; 

     Console.Read(); 
    } 

    public static void ChangeName(Person person) { 
     // This is a whole new person 
     var p = new Person() { Name = "Smith" }; 
     person = p; 
    } 

    public static void ChangeName2(Person person) { 
     person.Name = "Jerry"; 
    } 

    // This takes the reference and assigns a new person to the reference 
    public static void ChangeName(ref Person person) { 
     var p = new Person() { Name = "Smith" }; 
     person = p; 
    } 
} 

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