Question

一段简单的c++运算符重载的代码 各位帮忙看看错在哪里 我是没弄懂= =~新手 勿拍

#include<iostream.h>

class circle
{
private:
double radius;
public:
circle();
circle(double x);
friend int operator == (circle c1,circle c2);
friend int operator > (circle c1,circle c2);
friend void compare(circle c1,circle c2);
}

circle::circle()
{radius=(double)0;}

circle::circle(double x)
{radius=x;}

int operator == (circle c1,circle c2)
{
if (c1.radius==c2.radius)
return 1;
else
return 0;
}

int operator > (circle c1,circle c2)
{
if c1.radius>c2.radius
return 1;
else
return 0;
}

circle::compare(circle c1,circle c2)
{
if(c1==c2)
cout<<"c1,c2等大"<<
if(c1>c2)
cout<<"c1大于c2"<<
else
cout<<"c1小于c2"<<
}

void main()
{
circle c1(99);
circle c2(80);
compare(c1,c2);
}

编译显示的错误是：
[Error] C:\Users\fox\Documents\C-Free\Temp\未命名2.cpp:16: return type specification for constructor invalid
[Error] C:\Users\fox\Documents\C-Free\Temp\未命名2.cpp:31: parse error before `.'
[Error] C:\Users\fox\Documents\C-Free\Temp\未命名2.cpp:35: confused by earlier errors, bailing out

Answer 1

1、类的声明结束后，}后面要加分号
2、有几句代码后面没写分号
3、compare是友元函数，不是成员函数，不用加circle::
4、cout的最后不能是<<

#include<iostream.h>

class circle
{
private:
double radius;
public:
circle();
circle(double x);
friend int operator == (circle c1,circle c2);
friend int operator > (circle c1,circle c2);
friend void compare(circle c1,circle c2);
};

circle::circle()
{radius=(double)0;}

circle::circle(double x)
{radius=x;}

int operator == (circle c1,circle c2)
{
if (c1.radius==c2.radius)
return 1;
else
return 0;
}

int operator > (circle c1,circle c2)
{
if (c1.radius>c2.radius)
return 1;
else
return 0;
}

void compare(circle c1,circle c2)
{
if(c1==c2)
cout<<"c1,c2等大";
if(c1>c2)
cout<<"c1大于c2";
else
cout<<"c1小于c2";
}

void main()
{
circle c1(99);
circle c2(80);
compare(c1,c2);
}

Answer 2

#include<iostream.h>

class circle
{
private:
double radius;
public:
circle();
circle(double x);
friend int operator == (circle c1,circle c2);
friend int operator > (circle c1,circle c2);
friend void compare(circle c1,circle c2);
};//分号

circle::circle()
{radius=(double)0;}

circle::circle(double x)
{radius=x;}

int operator == (circle c1,circle c2)
{
if (c1.radius==c2.radius)
return 1;
else
return 0;
}

int operator > (circle c1,circle c2)
{
if (c1.radius>c2.radius)//前后括号
return 1;
else
return 0;
}

//circle:://不是成员函数，去掉类域名
void compare(circle c1,circle c2)
{
if(c1==c2)
cout<<"c1,c2等大"<<endl;//不完整，注意分号结束语句
if(c1>c2)
cout<<"c1大于c2"<<endl;//不完整，注意分号结束语句
else
cout<<"c1小于c2"<<endl;//不完整，注意分号结束语句
}

void main()
{
circle c1(99);
circle c2(80);
compare(c1,c2);
}