Can switch statements use variables?

Question

Below is code that declares two int variables and tries to use them in a switch statement. Is this a legal operation in C++? If not, why not?

Click to copy

int i = 0;
int x = 3;
switch (i)
{
    case x:
    // stuff
    break;

    case 0:
    // other stuff
    break;
}

Answer 1

The case label must be an integral constant expression, so your example is invalid. But if x were changed to:

Click to copy

const int x = 3;

then it's valid.