Question

I have the following code:

Code 1

class Student {
     int no;
     char grade[M+1];
 public:
     Student() {
         no = 0;
         grade[0] = '\0';
     }
     void set(int n, const char* g) {
         no = n;
         strcpy(grade, g);

     }
     const Student getObject() {
         return *this;
     }
     void display() const {
         cout << no << ", " << grade << endl;
     }
 };

Code 2:

// no change from code 1
const Student& getObject() {
         return *this;
     }
// no change from code 1

As the book I am reading explains the difference in the getObject() of the code 1 and 2 is that the getObject() of code 2 returns a reference to the current object, instead of a copy (for efficiency reasons).

However, I have tested (code 2) as follows:

Tested code:

Student harry, harry1;
    harry.set(123, "ABCD");

    harry1 = harry.getObject();
    harry1.set(1111,"MMMMMM");
    harry.display(); // Line 1 => displayed: 123, ABCD
    harry1.display(); / Line 2 => displayed: 1111, MMMMMM

I dont get it. If the getObject() returns a reference, then Line 1 in the tested code should also display 111, MMMMMM? Because I thought that harry1 should contain the address of harry object???
Or am I misunderstanding something?

Answer 1

Although harry.getObject() is a reference to the original object, you then ruin it with the assignment:

harry1 = harry.getObject();

which performs a copy.

Instead:

Student const& harry1 = harry.getObject();