#include
/* run this program using the console pauser or add your own getch, system("pause") or input loop /
using namespace std;
class Counter{
private:
int count;
public:
Counter(int i=0):count(i){}
Counter operator +(Counter&c)const{return Counter(count+c.count);}
Counter operator -(Counter&c)const{return Counter(count-c.count);}
Counter operator ++(){return Counter(++count);}
Counter operator ++(int){Counter c(*this);++(*this);return c;}
friend ostream&operator <<(ostream&out,Counter&c);
};
int main(int argc, char* argv) {
Counter c1(1),c2(2),c3(3),temp;
cout<<c1<<endl;
temp=(c1+c2);
cout<<temp<<endl;
temp=(c3-c1);
cout<<temp<<endl;
temp=(c3++)+c3+c3;
cout<<(c3++)<<endl;//重载了<<和++，这里为什么不能直接调用呢
cout<<c3<<endl;
temp=(++c1);
cout<<temp<<endl;
return 0;
}
ostream&operator <<(ostream&out,Counter&c){
out<<"The value of the counter:"<<c.count;
return out;
};
你的前++和后++估计都不行 因为<<的参数是Counter&c 而你的++返回值是Counter类型不匹配，你把++的返回值改为Counter&，再调整一下函数应该就只可以了
你的输出重载传的是引用，++重载返回的是值