提高效率
#include<iostream>
using namespace std;
class C{
public:
void set(int n){num=n;}
int get() const {return num;}
private:
int num;
};
void f(C& );
C& g();
int main()
{
C c1, c2;
f(c1);
c2=g();
cout<<c2.get()<<endl;
cout<<"***************"<<endl;
cout<<c1.get()<<endl<<c2.get()<<endl;
return 0;
}
void f(C& c){
c.set(-999);
cout<<c.get()<<endl;
}
C& g(){
static C c3;
c3.set(123);
return c3;
}