The return value of C + + is the case of the reference Reference---supplement (6) "Effective C + +" __c++

In the last blog we talked about returning a reference object may be wrong or inefficient, there is no more appropriate to return the reference reference. Let's summarize the types below:
1 function return value with reference, parameter pass in also use reference:

int& Hel (int& t) {return
    t;
}

2 function return value with reference, parameter pass with pointer

int& Hel (int *t) {return
    *t;
}

3 returns the data inside the function: Copy assignment operator

Class a{public
:
    A (int xx): x (XX) {
    }
    A () {

    }
    int GetX () const{return
        x;
    };
    void Show () {
        cout << x << endl;
    }
    A (const a&a) {
        this->x = a.x;
    }
    a& operator= (const a& A) {
        this->x = a.x;
        return *this;
    }
Private:
    int x;
};

Internal data

Class point{public
: Point
    (int x,int y);
    ...
    void SetX (int newval);
    void sety (int newval);
    ...
};
struct rectdata{point
    ulhc;
    Point lrhc;
};
Class rectangle{public
:
    ...
    point& upperleft () const 
    {return
    pdata->ulhc;
    }
    point& lowerright () const{return
    pdata->lrhc;
    }
Private:
    Rectangle pData;

The above two situations are more suitable for returning references, which is more efficient than the return object.
Reference Blog: http://www.cnblogs.com/lionfight/archive/2012/07/22/2603865.html