In C++, once a reference variable has been defined to refer to a particular variable, can it refer to any other variable?
My code I was using for testing is below:
int r1 =1001;
int r2 =10023;
int &r3 = r1;
r3 = r2;
r3 = 999;
r3 = 555;
int r4 = 11;
r3 = r4;
r3 = 10177;
cout<<r3<<endl;
cout<<r1<<endl;
cout<<r2<<endl;
cout<<r4<<endl;
The output:
10177
10177
10023
11
Once a reference variable has been defined to refer to a particular variable it can refer to any other variable in C plus plus?
No. References are bound at initialization and cannot be re-bound. After initialization, a reference is just an alias for the object it is bound to - and references must always be initialized.
In other words, whatever you do on the reference is done on the object being referenced. Here, for instance:
int &r3 = r1;
You are binding r3 to r1, so r3 will be an alias for r1 (like an alternative name). This means that the subsequent assignment:
r3 = r2;
Does not re-bind r3 to refer to r2: instead, it ends up assigning r2 to r1. Knowing this, you should be able to figure out the behavior of the rest of your program.
No, a reference can't be bound to another object after it has been initialised.
int r1 =1001;
int r2 =10023;
int &r3 = r1;
r3=r2;
Here, r3 is bound to the object r1 with value 1001. Then the name r3 behaves exactly as if you were using the name r1 instead - it's like an alias. When you assign the value of r2 to that object, r1 now contains the value 10023.
Here is your code with comments, which may help you understand:
int r1 = 1001; // r1 now holds the value 1001
int r2 = 10023; // r2 now holds the value 10023
int &r3 = r1; // using r3 is now like using r1
r3=r2; // same as r1=r2; r1 now holds the value 10023
r3 = 999; // same as r1 = 999; r1 now holds the value 999
r3 = 555; // same as r1 = 555; r1 now holds the value 555
int r4 = 11; // r4 now holds the value 11
r3=r4; // same as r1 = r4; r1 now holds the value 11
r3 = 10177; // same as r1 = 10177; r1 now holds the value 10177
cout<<r3<<endl; // same as printing r1 which is 10177
cout<<r1<<endl; // prints 10177
cout<<r2<<endl; // prints 10023
cout<<r4<<endl; // prints 11
r3 = r2;is assigning value of r2 to r3 not the reference. So they still point to different memory locations but with same values after this statement.