对象是引用类型还是值类型? [英] Is object a reference type or value type?

问题描述

我仍然对object存有疑问.它是任何类，任何类的主要基础类.但是它是引用类型还是值类型.还是喜欢这些行为中的哪一个?我需要弄清楚这一点.我很难理解.

I have still doubts about object. It is the primary base class of anything, any class. But is it reference type or value type. Or like which of these acts it? I need to get this clarified. I have difficulty understanding that.

     object obj1 = "OldString";
     object obj2 = obj1;
     obj1 = "NewString";
     MessageBox.Show(obj1 + "   " + obj2);
     //Output is  "NewString   OldString" 

在这种情况下，它的作用类似于值类型.如果对象是引用类型，那么为什么obj2值仍然是"OldString"

In this case it acts like a value type. If object was reference type then why obj2 value is still "OldString"

   class SampleClass
    {
        public string Text { get; set; }
    }

    SampleClass Sample1 = new SampleClass();
    Sample1.Text="OldText";         

    object refer1 = Sample1;
    object refer2 = refer1;

    Sample1.Text = "NewText";

    MessageBox.Show((refer1 as SampleClass).Text +  (refer2 as SampleClass).Text);
    //OutPut is "NewText   NewText"   

在这种情况下，它的作用类似于引用类型

In this case it acts like reference type

我们可以推断出object的类型就是您在其中键入的内容.它可以是引用类型，也可以是值类型.这是关于您在其中装箱的物品.我说的对吗?

We can deduce that object's type is what you box inside it. It can be both a reference type and value type. It is about what you box inside. Am I right?

推荐答案

它是引用类型

使用string进行示例不是很有启发性，因为string也是也是引用类型(显然，SampleClass也是)；您的示例包含零装箱".

Doing an example with string isn't very illuminating, because string is also a reference type (as is SampleClass, obviously); your example contains zero "boxing".

如果对象是引用类型，那么为什么obj2值仍为"OldString"

if object is reference type then why obj2 value is still "OldString"

为什么不呢?创建新字符串时，不会更改旧引用以指向新字符串.考虑:

Why wouldn't it be? When you create a new string, that doesn't change old references to point at the new string. Consider:

 object obj1 = "OldString";
 // create a new string; assign obj1 the reference to that new string "OldString"

object obj2 = obj1;
 // copy the reference from obj1 and assign into obj2; obj2 now refers to
 // the same string instance

 obj1 = "NewString";
 // create a new string and assign that new reference to obj1; note we haven't
 // changed obj2 - that still points to the original string, "OldString"

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