Question

If I write:

int a = 1;
int a = 2;

I get a compile time error, however if I write:

while(1) {
    int a = 1;
} 

no compile time error – whats the difference? does the while loop have its own scope or something?

Answer 1

In the second case, you don’t define multiple variables with the same name in the same scope. What happens is this

while(1)  { //there is no variable a in this scope
   int a = 1; //define a variable a at this point.
} //variable a is no more

In the first case, however, we have

int a = 1; //define variable a;

int a = 1; //variable a has been defined in this scope already, so error!