Sams Teach Yourself C++ in 21 Days

Exploiting References 259

9

Attempting to Reassign References (Not!) ....................................................

Reference variables cannot be reassigned. Even experienced C++ programmers can be

confused by what happens when you try to reassign a reference. Reference variables are

always aliases for their target. What appears to be a reassignment turns out to be the

assignment of a new value to the target. Listing 9.3 illustrates this fact.

LISTING9.3 Assigning to a Reference

1: //Listing 9.3 - //Reassigning a reference

2:

3: #include <iostream>

4:

5: int main()

6: {

7: using namespace std;

8: int intOne;

9: int &rSomeRef = intOne;

10:

11: intOne = 5;

12: cout << “intOne: “ << intOne << endl;

13: cout << “rSomeRef: “ << rSomeRef << endl;

14: cout << “&intOne: “ << &intOne << endl;

15: cout << “&rSomeRef: “ << &rSomeRef << endl;

16:

17: int intTwo = 8;

18: rSomeRef = intTwo; // not what you think!

19: cout << “\nintOne: “ << intOne << endl;

20: cout << “intTwo: “ << intTwo << endl;

21: cout << “rSomeRef: “ << rSomeRef << endl;

22: cout << “&intOne: “ << &intOne << endl;

23: cout << “&intTwo: “ << &intTwo << endl;

24: cout << “&rSomeRef: “ << &rSomeRef << endl;

25: return 0;

26: }

intOne: 5

rSomeRef: 5

&intOne: 0012FEDC

&rSomeRef: 0012FEDC

intOne: 8

intTwo: 8

rSomeRef: 8

&intOne: 0012FEDC

&intTwo: 0012FEE0

&rSomeRef: 0012FEDC

OUTPUT