定义桌子类与椅子类，要求比较它们的颜色是否相同，将比较颜色的函数定义为友函数

#include<iostream.h>

#include<string.h>

class Chair;

class Desk

{

char color[15];

friend int cmp(Desk,Chair);

public:

Desk(char *p)

{

strcpy(color,p);

}

};

class Chair

{

char color[15];

public:

friend int cmp(Desk,Chair);

Chair(char *p)

{

strcpy(color,p);

}

};

int cmp(Desk d,Chair c)

{

return strcmp(d.color,c.color);

}

void main()

{

Chair c1("red");

Desk d1("green");

if(cmp(d1,c1)==0)

cout<<"颜色相同"<<endl;

else

cout<<"颜色不相同"<<endl;

}