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#include"list.h"
class play{
public:
int music_play(list*);//用于播放列表歌曲
};
#include"play.h"
class list{
friend class play;//声明play类为友元类
public:
//代码省略
};
play.h(17):error C2061: 语法错误 : 标识符“list”
#include"list.h"
class play{
public:
int music_play(list*);//用于播放列表歌曲
};
class play;
class list{
friend class play;//声明play类为友元类
public:
//代码省略
};
#include<iostream>
#include<cstdlib>
using namespace std;
class A
{
int x,y;
public:
A(int x,int y):x(x),y(y){};
friend class B;
};
class B
{
int x,y;
public:
B(A a);
void print(A a);
};
B::B(A a)
{
x=a.x;
y=a.y;
}
void B::print(A a)
{
cout<<a.x<<endl<<a.y<<endl;
cout<<x<<endl<<y<<endl;
}
int main()
{
A a(2,3);
B b(a);
b.print(a);
system("pause");
return 0;
}