Switch question

Question

How can l write this with the '' switch'' statement:

int a;
cin a;

switch(a)
case a>0:
cout....
break;
case a<0:
cout...
break;

I want to replace the if statement, but the switch statement does not work because' a' is not a cobstant variable. Is there a way to write a unconstant variable in the 'case' row?
PS:I want to use exactly the switch statement

Answer 1

switch(a >= 0) {
case 1:
cout << (...);
break;
case 0:
cout << (...);
break;
}

Answer 2

Partialy true. The case arguments must be constant, means no expression.