C# 重载类型运算符

在C#中我们可以使用 operator 关键字来重载运算符,首先先来看看哪些运算符能够被重载

Operators	Overloadability
+, -, !, ~, ++, --, true, false	These unary operators can be overloaded.
+, -, *, /, %, &, |, ^, <<, >>	These binary operators can be overloaded.
==, !=, <, >, <=, >=	The comparison operators can be overloaded (but see the note that follows this table).
&&, ||	The conditional logical operators cannot be overloaded, but they are evaluated using & and |, which can be overloaded.
[]	The array indexing operator cannot be overloaded, but you can define indexers.
(T)x	The cast operator cannot be overloaded, but you can define new conversion operators (seeexplicit and implicit).
+=, -=, *=, /=, %=, &=, |=, ^=, <<=, >>=	Assignment operators cannot be overloaded, but +=, for example, is evaluated using +, which can be overloaded.
=, ., ?:, ??, ->, =>, f(x), as, checked, unchecked, default, delegate, is,new, sizeof, typeof	These operators cannot be overloaded.

那么要怎么使用 operator 关键字呢?看看下面的代码就能很快明白了

    class Program
    {
        static void Main(string[] args)
        {
            Test t1 = new Test() { count=1, value=10 };
            Test t2 = new Test() { count=1, value=10 };
            Test tr = t1 + t2;
            Console.WriteLine(tr.ToString());//count:2   value:20
            Console.WriteLine("按任意键结束");
            Console.Read();
        }
    }


    public class Test
    {
        public int value;
        public int count;

        public static Test operator +(Test test1, Test test2)
        {
            Test testresult = new Test();
            testresult.count = test1.count + test2.count;
            testresult.value = test1.value + test2.value;
            return testresult;
        }

        public override string ToString()
        {
            return string.Format("count:{0}   value:{1}", this.count, this.value);
        }
    }

这里我定义了一个 名叫Test的类,并且重写了他相加的运算符.这样我想让两个Test类型相加时就可以使用自定义的相加逻辑了.
当然,其他的运算符重写也是同样道理.
这里要说一下,判断用的运算符需要成对重写,比如 == 和 !=