Question

Here is my test code:

#define print(A) cout << #A <<  " = " << A <<  endl;
int main()
{
    const int e = 2;
    int *p = (int *)&e;
    *p = 4;

    print(e);
    print(*p);
    print(&e);
    print(p);
}

Result:

e = 2;
*p = 4;
&e = 0xbfc6b458;
p = 0xbfc6b458;

Since “p” points to “e” according to their identical address, how can *p and “e” be different??? This can be dangerous, right?

Answer 1

Casting away const is legal; using the pointer (or reference) thus acquired to (attempt to) modify a const object is illegal.

Your code results in undefined behaviour; it can do anything and it doesn’t have to make any sense.