Question

I don’t understand why such a code can’t build:

if (SomeCondition) {
    Boolean x = true;
} else {
    Boolean x = false;
}
Debug.WriteLine(x);     // Line where error occurs

It creates the following error:

The name ‘x’ does not exist in the current context

For me, x is declared in all cases because there is an else clause. So why the compiler don’t know it on the Debug.WriteLine line?

Answer 1

It is due to block scoping of variables: { int x = 3; } is only visible inside the block. You should move the declaration of x outside the block:

Boolean x;

if (SomeCondition) {
     x = true;
} else {
    x = false;
}
Debug.WriteLine(x);    

Or in the above case, even better:

bool x = SomeCondition;
Debug.WriteLine(x);