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c#中委托和事件有什么关系和区别`??

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c#中委托和事件有什么关系和区别`??

发表于：2007-04-12 18:36:48 楼主

我是一名在校大学生``
在学习c#.net`~
但是关于这个的``
我没听明白,望各位大哥大姐教一下?

发表于：2007-04-12 18:38:121楼得分:0

using system;

namespace exam
{
public delegate void delegateendexam（datetime t,student s);//委托

public class student
{
private string _name;
public event delegateendexam finishexam;

public student（string name)
{
_name=name;
}

public void begintest（datetime bt)
{
console.writeline（ "{0}\t{1}开始答题 ",_name,bt);
}

public void handinpaper（)
{
console.writeline（ "{0}\t答题完成 ",this.tostring（));
finishexam（datetime.now,this);
}

public override string tostring（)
{
return _name;
}

}

public delegate void delegatebeginexam（datetime t);

class teacher
{
public event delegatebeginexam beginexam;

public teacher（)
{}

public void sendbeginexam（)
{
beginexam（datetime.now);
}

public void acceptpaper（datetime t,student s)
{
console.writeline（ "收{0}\t的试卷 ",s.tostring（));
}

}

public class exam
{
public exam（)
{}

public static void main（)
{
teacher teacher=new teacher（);
student[] students=new student[5];
int index=0;
students[index++]=new student（ "jack ");
students[index++]=new student（ "tom ");
students[index++]=new student（ "jim ");
students[index++]=new student（ "baker ");
students[index++]=new student（ "lucy ");

foreach（student tr in students)
{
teacher.beginexam+=new delegatebeginexam（tr.begintest);
tr.finishexam+=new delegateendexam（teacher.acceptpaper);
}

teacher.sendbeginexam（);
foreach（student stu in students)
{
stu.handinpaper（);
}
}
}
}

发表于：2007-04-12 18:38:442楼得分:0

http://kv4000.cnblogs.com/articles/122128.aspx

发表于：2007-04-12 18:39:443楼得分:0

看msdn中讲述“委托”的章节。权威准确。

发表于：2007-04-12 19:36:444楼得分:0

我这两天也在研究这东西，，给你几个关于委托的例子，都是调试通过的，

1、
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visual basic 复制代码
imports system

public class samplesdelegate

' declares a delegate for a method that takes in an int and returns a string.
delegate function mymethoddelegate（myint as integer) as [string]

' defines some methods to which the delegate can point.
public class mysampleclass

' defines an instance method.
public function mystringmethod（myint as integer) as [string]
if myint > 0 then
return "positive "
end if
if myint < 0 then
return "negative "
end if
return "zero "
end function 'mystringmethod

' defines a static method.
public shared function mysignmethod（myint as integer) as [string]
if myint > 0 then
return "+ "
end if
if myint < 0 then
return "- "
end if
return " "
end function 'mysignmethod
end class 'mysampleclass

public shared sub main（)

' creates one delegate for each method.
dim mysc as new mysampleclass（)
dim myd1 as new mymethoddelegate（addressof mysc.mystringmethod)
dim myd2 as new mymethoddelegate（addressof mysampleclass.mysignmethod)

' invokes the delegates.
console.writeline（ "{0} is {1}; use the sign " "{2} " ". ", 5, myd1（5), myd2（5))
console.writeline（ "{0} is {1}; use the sign " "{2} " ". ", - 3, myd1（- 3), myd2（- 3))
console.writeline（ "{0} is {1}; use the sign " "{2} " ". ", 0, myd1（0), myd2（0))

end sub 'main

end class 'samplesdelegate

'this code produces the following output:
'
'5 is positive; use the sign "+ ".
'-3 is negative; use the sign "- ".
'0 is zero; use the sign " ".

c# 复制代码
using system;
public class samplesdelegate {

// declares a delegate for a method that takes in an int and returns a string.
public delegate string mymethoddelegate（ int myint );

// defines some methods to which the delegate can point.
public class mysampleclass {

// defines an instance method.
public string mystringmethod （ int myint ) {
if （ myint > 0 )
return（ "positive " );
if （ myint < 0 )
return（ "negative " );
return （ "zero " );
}

// defines a static method.
public static string mysignmethod （ int myint ) {
if （ myint > 0 )
return（ "+ " );
if （ myint < 0 )
return（ "- " );
return （ " " );
}
}

public static void main（) {

// creates one delegate for each method.
mysampleclass mysc = new mysampleclass（);
mymethoddelegate myd1 = new mymethoddelegate（ mysc.mystringmethod );
mymethoddelegate myd2 = new mymethoddelegate（ mysampleclass.mysignmethod );

// invokes the delegates.
console.writeline（ "{0} is {1}; use the sign \ "{2}\ ". ", 5, myd1（ 5 ), myd2（ 5 ) );
console.writeline（ "{0} is {1}; use the sign \ "{2}\ ". ", -3, myd1（ -3 ), myd2（ -3 ) );
console.writeline（ "{0} is {1}; use the sign \ "{2}\ ". ", 0, myd1（ 0 ), myd2（ 0 ) );
}

}

/*
this code produces the following output:

5 is positive; use the sign "+ ".
-3 is negative; use the sign "- ".
0 is zero; use the sign " ".
*/

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发表于：2007-04-12 19:37:555楼得分:0

2、
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using system;

public class delcls
{
public delegate void deldef（params string[] strparams);

public static void calldel（deldef dd)
{
if（dd != null) //请务必在此处进行判断，这是个好习惯
{
dd（ "hello ", "world ");
}
}
}

public class delins
{
//声明为private（私有）成员并不影响在类型内部使用委托
private static void clscallstr（params string[] strparams) //类型方法
{
//将字符串数组并顺序输出
foreach（string str in strparams)
{
console.write（ "{0} ",str);
}
console.writeline（ );
}

public void inscallstr（params string[] strparams) //实例方法
{
//将字符串数组并反序输出
for（int i = strparams.length - 1; i > = 0; i--)
{
console.write（ "{0} ",strparams[i]);
}

console.writeline（ );
}

public static void main（ )
{
delins di = new delins（ );
delcls.deldef dd = null;
console.writeline（ "combine two delegate: ");
dd += new delcls.deldef（delins.clscallstr);
dd += new delcls.deldef（di.inscallstr);

dd.getinvocationlist（ );//返回委托链中的内容。

delcls.calldel（dd);

console.writeline（ "remove the first delegate: ");
dd -= new delcls.deldef（delins.clscallstr);
delcls.calldel（dd);

}

}

发表于：2007-04-12 19:40:386楼得分:0

个人理解
通常意义上的委托是一种编程的方法和思想。而事件，是实现这种方法的一个典型代表

发表于：2007-04-12 19:59:517楼得分:0

delegate是event他爹兼他妈~

发表于：2007-04-12 22:08:198楼得分:0

谢谢各位`~
不知能否将注释写进去`~

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