C++笔记(6)友元
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1#include <iostream>
2using namespace std;
3class Internet
4{
5public:
6 Internet(char *name,char *address)
7
{
8 strcpy(Internet::name,name);
9 strcpy(Internet::address,address);
10 }
11friend void ShowN(Internet &obj);//友元函数的声明
12public:
13 char name[20];
14 char address[20];
15};
16
17
18void ShowN(Internet &obj)//函数定义,不能写成,void Internet::ShowN(Internet &obj)
19{
20 cout<<obj.name<<endl;
21}
22void main()
23{
24 Internet a("中国软件开发实验室","www.cndev-lab.com");
25 ShowN(a);
26 cin.get();
27}
一个普通函数可以是多个类的友元函数,对上面的代码我们进行修改,注意观察变化:
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一个类的成员函数函数也可以是另一个类的友元,从而可以使得一个类的成员函数可以操作另一个类的数据成员,我们在下面的代码中增加一类Country,注意观察:
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整个类也可以是另一个类的友元,该友元也可以称做为友类。友类的每个成员函数都可以访问另一个类的所有成员。
示例代码如下:
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在上面的代码中我们成功的通过Internet类Editcname成员函数操作了Country类的保护成员cname。
在编程中,我们使用友元的另外一个重要原因是为了方便重载操作符的使用,这些内容我们将在后面的教程着重讨论!
参考:
http://www.pconline.com.cn/pcedu/empolder/gj/c/0503/571623_1.html
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