I don't get the const Pointer

[T98]

I've written following code:

int c = 5;
int const * const d = &c;
c +=1;
cout << *d; //here the Output is 6 (why?)
cout << c;  //here the Output is 6 - Which must be the case 

Why does the value of d still changes if it is constant?
Is it possible to have Pointer with a constant value which can't be changed?

It might be an easy question. But it's not so easy to understand for me. Thanks for the answer anyway.

[Peter87]

When you have a pointer (or reference) to a const it simply means you are not allowed to use that pointer to modify the value.

*d = 5; // error 

You can still modify the value if you have some non-const access to it. If you don't want c to change you could define it as const.

int const c = 5;
int const * const d = &c;

Now you are not allowed to change the value of c.

If you don't want *d to change when c is changed you probably don't want to use a pointer. You could make d a const copy of c instead.

int c = 5;
int const d = c;

Now the value of d will always stay the same, even if c is changed.

[T98]

Thanks a lot. I think I got the point of using pointer and const.