Question

Suppose this is the call stack of my program at a particular point:

|    b = 2       |
|    c = 3       | <- function f2
| return address |
| function args  |
|     ...        |
|    c = 10      | <- function f1
|     ...        |

f1() calls f2().

When variable c is referenced, how is it resolved? Is the stack searched linearly top down to find the first variable named c in scope, or is there some other mechanism that takes care of this more efficiently?

If the stack is searched every time, wont it be an overhead when a non existent variable d is referenced, because the stack will be searched all the way to find out that there is no such variable in scope?

Answer 1

In C++, during runtime the variables don’t have names. Variable names are only there for the convenience of the programmer. Variables have scope in the code, they don’t have a scope in the stack.

So the stack is not searched during runtime. During compilation the variable name is converted into a memory address.