C# 对象的深复制和浅复制

2019年第一篇博客，好吧，又大了一岁了，继续加油吧。

正文：

    C# 中的对象，众所周知是引用类型，那么如何复制对象Object呢，我们来看看下面这段代码：

public class User
    {
        public int UserId { get; set; }

        public string UserName { get; set; }

        public string PassWord { get; set; }

        public DateTime AddTime { get; set; }

        public User(int UserId, string UserName, string PassWord, DateTime AddTime)
        {
            this.UserId = UserId;
            this.UserName = UserName;
            this.PassWord = PassWord;
            this.AddTime = AddTime;
        }
    }

    public class People
    {
        public string abc { get; set; }
        public User User { get; set; }

        public People ShallowCopy()
        {
            return (People) this.MemberwiseClone();
        }

        public People DeepCopy()
        {
            People other = (People)this.MemberwiseClone();
            other.User = new User(User.UserId, User.UserName, User.PassWord, User.AddTime);

            other.abc = String.Copy(abc);
            return other;
        }
    }

            People people = new People
            {
                abc = "1",
                User = new User(1,"1","1",DateTime.Now)
            };
            People people4 = people;
            people.abc = "23";
            people.User.PassWord = "2";            

我们可以看到 将对象people 赋给了people4，那么我们修改people的值  people4 的值会如何呢？我们打断点试试，

 

我们可以看到people 和people4的值是一样的，什么原理呢，原来people4只是people的引用，people4指向people的地址，所以people的值改变，实际上people4引用的值就是people的地址，所以他们的值是一样的。

那么都是一样的话，我们需要怎么才能复制对象，而不是引用呢，

可以看到上面的代码中people类中定义了两个方法 ShallowCopy() 和 DeepCopy()，那这两个方法有什么作用呢，首先我们来看下面这段代码:

            People people = new People
            {
                abc = "1",
                User = new User(1,"1","1",DateTime.Now)
            };
            People people2 = people.ShallowCopy(); //浅拷贝方法
            People people3 = people.DeepCopy();    //深拷贝方法
            people.abc = "23";
            people.User.PassWord = "2";

那这里 people2 和people3 的值是什么呢，打断点看看：

我们可以看到的是，people的值改变之后，people2中abc的值并没有改变，但是people2中User 中的password的值已经改变了，这就是对象的浅拷贝，是因为浅拷贝对象people2中的object类型指向的地址还是people的地址。

而people3 是深拷贝，深复制了一个新的对象，地址和原对象people不同，所以people的值改变，people3的值不会变。

这就是深拷贝和浅拷贝的区别。That's all, thank you