C#控制台应用程序提示‘只能出现在+=或-=左边’

Question

using System;
using System.Collections.Generic;
using System.Text;
namespace Delegate
{
public delegate void GreetingDelegate(string name);

public class GreetingManager
{
public event GreetingDelegate MakeGreet;
public void GreetPeople(string name, GreetingDelegate MakeGreeting)
{
MakeGreeting(name);
}
}
class Program
{
private void EnglishGreeting(string name)
{
Console.WriteLine("Morning, " + name);
}
private void ChineseGreeting(string name)
{
Console.WriteLine("早上好, " + name);
}

static void Main(string[] args)
{
GreetingManager gm = new GreetingManager();
Program p = new Program();
gm.MakeGreet = p.EnglishGreeting;
gm.MakeGreet += p.ChineseGreeting;
gm.GreetPeople("name", gm.MakeGreet);

}
}
}

Answer 1

因为你定义的MakeGreet是事件，而事件必须使用加法赋值运算符 (+=) 来为事件附加事件处理程序，使用减法赋值运算符 (-=) 取消订阅事件
不支持其它的运算符

参考微软MSDN:
http://msdn.microsoft.com/zh-cn/library/ms366768.aspx

Answer 2

gm.MakeGreet = p.EnglishGreeting;
改成
gm.MakeGreet += p.EnglishGreeting;

Answer 3

LZ这样试一下：
GreetingDelegate delegate1;
delegate1 = EnglishGreeting; // 先给委托类型的变量赋值
delegate1 += ChineseGreeting; // 给此委托变量再绑定一个方法
应该是可以的，如果按你写的就要把
gm.MakeGreet = p.EnglishGreeting;
改成
gm.MakeGreet += p.EnglishGreeting; //给事件注册方法

可以搜索下委托与事件的资料，呵呵