C#的一個事件問題

Question

using System;
namespace example
{
    
    public class Test
    {
        public delegate void delegateEnter();
        public event delegateEnter ZeroEntered;
        public  int _num1;
        public  int _num2;
        public Test(int n1,int n2)
        {
            _num1 = n1;
            _num2 = n2;
        }
        public void Disp()
        {
            if (_num2 == 0)
            {
                Console.WriteLine("除數不能為0");
                return;
            }
            ZeroEntered();
        }
    }    class TestEnter
    {
        public int num = 1;
        public int num2 = 2;
        static void Main()
        {
            Console.WriteLine("輸入數據中");
            
            Test obj  = new Test(1,2);
            obj.ZeroEntered += new Test.delegateEnter(TestEnter.answer);  －－－－>這裡報的錯，請問是什麼問題呢？
            obj.Disp();
        }
        public void answer()
        {
            Console.WriteLine("答案是{0}.", this.num / this.num2);
        }
    }
}

Answer 1

是用來判斷如果NUM2為0就提示錯誤，如果NUM2不等於0就把NUM除NUM2的結果輸出，請問應該怎麼做呢？ 

Answer 2

 public   class   Test 
        { 
                public   delegate   void   delegateEnter(); 
                public   event   delegateEnter   ZeroEntered; 
                public     int   _num1; 
                public     int   _num2; 
                public   Test(int   n1,int   n2) 
                { 
                        _num1   =   n1; 
                        _num2   =   n2; 
                } 
                public   void   Disp() 
                { 
                        if   (_num2   ==   0) 
                        { 
                                Console.WriteLine("除數不能為0"); 
                                return; 
                        } 
                        if(ZeroEntered != null)
                        ZeroEntered(); 
                } 
        } 

Answer 3

public       class       Test   
                {   
                                public       delegate       void       delegateEnter();   
                                public       event       delegateEnter       ZeroEntered;   
                                public           int       _num1;   
                                public           int       _num2;   
                                public       Test(int       n1,int       n2)   
                                {   
                                                _num1       =       n1;   
                                                _num2       =       n2;   
                                }   
                                public       void       Disp()   
                                {   
                                                if       (_num2       ==       0)   
                                                {   
                                                                Console.WriteLine("除數不能為0");   
                                                                return;   
                                                }   
                                                if(ZeroEntered   !=   null) //注意这里
                                                ZeroEntered();   
                                }   
                }   

Answer 4

           public   class   Test 
        { 
                public   delegate   void   delegateEnter(); 
                public   event   delegateEnter   ZeroEntered; 
                public     int   _num1; 
                public     int   _num2; 
                public   Test(int   n1,int   n2) 
                { 
                        _num1   =   n1; 
                        _num2   =   n2; 
                } 
                public   void   Disp() 
                { 
                        if   (_num2   ==   0) 
                        { 
                                Console.WriteLine("除數不能為0"); 
                                return; 
                        } 
                        ZeroEntered(); 
                } 
        }         class   TestEnter 
        { 
                public   int   num   =   1; 
                public   int   num2   =   2; 
                static   void   Main() 
                { 
                        Console.WriteLine("輸入數據中"); 
                        
                        Test   obj     =   new   Test(1,2);
                        obj.ZeroEntered += new Test.delegateEnter(obj.Disp);
                        //obj.Disp(); 
                } 
                public   void   answer() 
                { 
                        Console.WriteLine("答案是{0}.",   this.num   /   this.num2); 
                } 
        } 这样就不会报错，不过好像不是这样用的

Answer 5

楼上的一群猪猪！！！
class   TestEnter
{
  public   int   num   =   1;
  public   int   num2   =   2;
  static   void   Main()
  {
    Console.WriteLine("輸入數據中");    Test   obj     =   new   Test(1,2);
    obj.ZeroEntered   +=   new   Test.delegateEnter(TestEnter.answer);     －－－－> 這裡報的錯，請問是什麼問題呢？
    obj.Disp();
  }
  public   void   answer()
  {
    Console.WriteLine("答案是{0}.",   this.num   /   this.num2);
  }
} 
注意上段代码中的红色部分！！！
非静态方法怎么能在静态方法中调用呢？？？

Answer 6

正确的为[code=C#]
public delegate void delegateEnter (int num1, int num2);public class Test
{
  public event delegateEnter ZeroEntered;
  public int _num1;
  public int _num2;
  public Test (int n1, int n2)
  {
    _num1 = n1;
    _num2 = n2;
  }
  public void Disp ()
  {
    if (_num2 == 0)
    {
      Console.WriteLine("除數不能為0");
      return;
    }
    ZeroEntered(_num1, _num2);
  }
}class TestEnter
{
  static void Main()
  {
    Console.WriteLine("輸入數據中");    Test obj = new Test(1,2);
    obj.ZeroEntered += new delegateEnter(answer);
    obj.Disp();
  }  public static void answer(int num1, int num2)
  {
    Console.WriteLine("答案是{0}.", num1 / num2);
  }
}