C＃中的Object.MemberwiseClone方法与示例

Object.MemberwiseClone方法用于创建当前对象的浅表副本或进行克隆。浅拷贝是对象的按位拷贝。在这种情况下，将创建一个新对象，并且该对象具有现有对象的精确副本。基本上，此方法将当前对象的非静态字段复制到新对象。

• 如果字段是引用类型，则仅复制引用，而不复制引用的对象。因此，在这里，克隆的对象和原始对象将引用相同的对象。
• 如果该字段是值类型，则将执行该字段的逐位复制。

句法：

protected object MemberwiseClone ();

返回：此方法返回一个Object ，它是现有Object的浅表副本。

范例1：

// C# program to clone a object
// using MemberwiseClone() method
using System;
  
class GFG1 {
  
    public int val;
  
    public GFG1(int val)
    {
        this.val = val;
    }
      
}
  
class GFG2 {
  
    public GFG1 gg;
  
    public GFG2(int val)
    {
        // copy the reference of GFG1 to gg
        this.gg = new GFG1(val);   
    }
  
    // method for cloning
    public GFG2 Clone()
    {
        // return cloned value using
        // MemberwiseClone() method
        return ((GFG2)MemberwiseClone());
         
    }
}
  
// Driver Code
class Geek {
  
  
    // Main Method
    public static void Main()
    {
        // object of Class GFG2 with a value 3
        GFG2 g = new GFG2(3);
          
        // calling Clone()
        // "cc" has the reference of Clone()
        GFG2 cc = g.Clone();
         
        // accessing the main value
        Console.WriteLine("Value: " + g.gg.val);
          
        // accessing the cloned value
        Console.WriteLine("cloned value: " + cc.gg.val);
          
        // set a new value 
        // in variable "val"
        cc.gg.val = 6;
          
        // accessing the main value
        Console.WriteLine("\nValue: " + g.gg.val);
         
        // accessing the cloned value
        Console.WriteLine("cloned value: " + cc.gg.val);
          
    }
}

输出：

Value: 3
cloned value: 3

Value: 6
cloned value: 6

范例2：

// C# program to demonstrate the 
// MemberwiseClone() method
using System;
  
public class GFG : ICloneable {
  
    // data members
    public string Name;
    public string Surname;
    public int Age;
  
    // constructor
    public GFG(string name, 
     string title, int age)
    {
        Name = name;
        Surname = title;
        Age = age;
    }
  
    // method for cloning
    public object Clone()
    {
        // return cloned value using
        // MemberwiseClone() method
        return MemberwiseClone();   
    }
  
    public override string ToString()
    {
        return string.Format("Name = {0}, Surname = {1}, Age {2}",
                                              Name, Surname, Age);
    }
}
  
// Driver Class
public class MainClass {
  
    // Main Method
    public static void Main()
    {
        GFG g = new GFG("ABC", "XYZ", 26);
  
        // calling Clone()
        // "cg" has reference of Clone()
        GFG cg = (GFG)g.Clone();
          
        Console.WriteLine("For Old values\nOriginal :");
        Console.WriteLine(g);
  
        Console.WriteLine("Cloned :");
        Console.WriteLine(cg);
  
        Console.WriteLine("\nAfter assigning new values");
        g.Name = "LMN";
        g.Surname = "QRS";
        g.Age = 13;
  
        Console.WriteLine("Original :");
        Console.WriteLine(g);
  
        Console.WriteLine("Cloned :");
  
        // prints the old colned value
        Console.WriteLine(cg);
          
    }
}

输出：

For Old values
Original :
Name = ABC, Surname = XYZ, Age 26
Cloned :
Name = ABC, Surname = XYZ, Age 26

After assigning new values
Original :
Name = LMN, Surname = QRS, Age 13
Cloned :
Name = ABC, Surname = XYZ, Age 26

参考：

• https://docs.microsoft.com/zh-cn/dotnet/api/system.object.memberwiseclone?view=netframework-4.8