无法过载！=操作员因错误3而需要匹配的操作员？ [英] Unable To Overload != Operator Due To Error 3 requires a matching operator ?

问题描述

无法过载！=，错误3操作员'ConsoleApplication13.pl.operator！=（ConsoleApplication13.pl，ConsoleApplication13.pl）'需要匹配的运算符'=='也要定义C：\ Users \ htg\documents\visual studio 2013 \Projects\ConsoleApplication13 \ConsoleApplication13 \Program.cs 37 28 ConsoleApplication13。 t $ / b

Unable To Overload != , Error 3 The operator 'ConsoleApplication13.pl.operator !=(ConsoleApplication13.pl, ConsoleApplication13.pl)' requires a matching operator '==' to also be defined C:\Users\htg\documents\visual studio 2013\Projects\ConsoleApplication13\ConsoleApplication13\Program.cs 37 28 ConsoleApplication13 . t

class Program
    {
        static void Main(string[] args)
        {
            pl a ,b,c;
           a= new pl();
            b=new pl();
            a.mark=99;
            b.mark=10;
            c = a+b;
            if (c != b)
                Console.WriteLine("is not equal");
            else
                Console.WriteLine("both are equal");
            Console.WriteLine(c.mark);
           Console.ReadLine();
        }
    }
    class pl
    {
        public int mark;
        public static pl operator+ ( pl a , pl b) // 1. here It Work's Perfectly At + overloading
        {
            pl mm = new pl();
            mm.mark = a.mark + b.mark;
            return mm;

        }
        public static bool operator!= (pl m , pl n) // 2. unable to overload
        {
            if (m.mark != n.mark)
                return true;
            else
                return false;
        }       
    }

推荐答案

是的，需要为==和！=实现重载if你实现了其中一个。



有一个非常标准的方法，你也应该实现.Equals方法的重叠：

Yes, it is required to implement overloads for both == and != if you implement one of them.

There's a very standard way of doing this, and you should also implement an over-ride for the .Equals method:

public class SomeClass
{
    public string ClassName { set; get; }

    public SomeClass(string name)
    {
        ClassName = name;
    }

    protected bool Equals(SomeClass other)
    {
        return string.Equals(ClassName, other.ClassName);
    }

    public override bool Equals(object obj)
    {
        if (ReferenceEquals(null, obj)) return false;
        if (ReferenceEquals(this, obj)) return true;
        if (obj.GetType() != this.GetType()) return false;
        return Equals((SomeClass)obj);
    }

    public override int GetHashCode()
    {
        return (ClassName != null ? ClassName.GetHashCode() : 0);
    }

    public static bool operator ==(SomeClass c1, SomeClass c2)
    {
        return c1.ClassName == c2.ClassName;
    }

    public static bool operator !=(SomeClass c1, SomeClass c2)
    {
        return !(c1 == c2);
    }
}

这不是一个问题，但不难看出你缺少什么。您需要实现==和！=（或者都不是）。如果您考虑一下，您可能会理解这是一个非常合乎逻辑的规则。

-SA

This is not a question, but it's not hard to see what you are missing. It is required that you implemented both == and != (or none of them). If you think about it, you may understand that this is a pretty logical rule.

—SA

这篇关于无法过载！=操作员因错误3而需要匹配的操作员？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！