C＃与结构内的列表混淆（值类型与引用类型）(C# Confused with a list inside a struct (value type vs reference type))

 所以今天我发现当用于在C＃中赋值变量时，结构和类的行为有所不同。据我所知，当我将一个结构赋给变量时，变量存储该结构的副本，当我分配一个类时对于变量，变量存储对该类实例的引用。 
 
 在这种情况下，dad2包含一个dad1的副本，所以我不应该对dad2做什么不影响dad1？ 事实并非如此，因为当我向dad2添加一个儿子时，它也会向dad1添加相同的儿子。 
 
public struct Dad {
        public string name;
        public List <Son> sons;

        public struct Son {
            public string name;

            public Son (string n) {
                name = n;
            }
        }
    }

    static void Main (string [] args) {
        Dad dad1 = new Dad ();
        dad1.name = "Bob";
        dad1.sons = new List <Dad.Son> {new Dad.Son ("A")};

        Dad dad2 = dad1;
        Debug.WriteLine (dad2.Equals (dad1) + " " + dad1.sons.Count () + " " + dad2.sons.Count ());
        //true 1 1
        dad2.sons.Add ( new Dad.Son ("B"));
        Debug.WriteLine (dad2.Equals (dad1) + " " + dad1.sons.Count () + " " + dad2.sons.Count ());
        //true 2 2
    }

So I found out today that structs and classes act differently when used to assign to variables in C#.. It's to my understanding that when I assign a struct to a variable, the variable stores a copy of that struct, and when I assign a class to a variable, the variable stores the reference to that class instance.
 
In this case, dad2 contains a copy of dad1, so shouldn't anything I do to dad2 not affect dad1? It's not the case apparently because when I add a son to dad2 it also adds the same son to dad1.
 
public struct Dad {
        public string name;
        public List <Son> sons;

        public struct Son {
            public string name;

            public Son (string n) {
                name = n;
            }
        }
    }

    static void Main (string [] args) {
        Dad dad1 = new Dad ();
        dad1.name = "Bob";
        dad1.sons = new List <Dad.Son> {new Dad.Son ("A")};

        Dad dad2 = dad1;
        Debug.WriteLine (dad2.Equals (dad1) + " " + dad1.sons.Count () + " " + dad2.sons.Count ());
        //true 1 1
        dad2.sons.Add ( new Dad.Son ("B"));
        Debug.WriteLine (dad2.Equals (dad1) + " " + dad1.sons.Count () + " " + dad2.sons.Count ());
        //true 2 2
    }

原文：https://stackoverflow.com/questions/6811447