C#引用数据类型特点以及ref的使用

红太狼 2021-11-17 02:28 203阅读 0赞

先贴代码

namespace ConsoleApplication6
    {
        class Program
        {
            static void Main(string[] args)
            {
                Test1();
                Test2();
                Test3();
            }
            private static void Test1()
            {
                var a = new DataModel() { Value = 1 };
                var b = a;
                a = new DataModel() { Value = 2 };
                Console.WriteLine($"a = {a.Value}");
                Console.WriteLine($"b = {b.Value}");
    
                //Output: a=2 b=1
            }
            private static void Test2()
            {
                var a = new DataModel() { Value = 1 };
                ChangeVal(a);
                Console.WriteLine($"a = {a.Value}");
                //Output: a=1 b=1 c=2
            }
            private static void Test3()
            {
                var a = new DataModel() { Value = 1 };
                ChangeVal(ref a);
                Console.WriteLine($"a = {a.Value}");
                //Output: a=2 b=1 c=2
            }
    
    
            private static void ChangeVal(DataModel c)
            {
                var b = c;
                c = new DataModel() { Value = 2 };
                Console.WriteLine($"b = {b.Value}");
                Console.WriteLine($"c = {c.Value}");
            }
    
            private static void ChangeVal(ref DataModel c)
            {
                var b = c;
                c = new DataModel() { Value = 2 };
                Console.WriteLine($"b = {b.Value}");
                Console.WriteLine($"c = {c.Value}");
            }
        }
    
        public class DataModel
        {
            public int Value { get; set; }
        }
    }

Test1() b=a之后b指向了同一块内存地址，a重新赋值后a指向了另一块内存地址

![399098-20190709102024668-1211200256.png][]

Test2() 函数传递参数，实际地址发生了改变，参数重新实例化后，指向了另一个内存地址

![399098-20190709102235884-7536418.png][]

Test3() 使用ref关键字后传递了一样的地址，所以后面修改c的值就是修改a的值

![399098-20190709102437515-647280096.png][]

转载于:https://www.cnblogs.com/qidong/p/11155708.html

[399098-20190709102024668-1211200256.png]: /images/20211116/ae3fd200452d48949773a7637233bf56.png
[399098-20190709102235884-7536418.png]: /images/20211116/a18e679bdd8e416aa30d263b1ffe70f3.png
[399098-20190709102437515-647280096.png]: /images/20211116/fd8d7be3ba3545d0800e93aee783792d.png