class String{
string s;
public:
    void getS(){cout<<s;}
    void setS(){cin>>s;}
    String operator=(String a){
        String b;
        b.s=a.s;
        return b;
    }
};
int main(){
    String a;a.setS();
    String b;b=a;
    b.getS();//no output
}
//why no output?