Identical memory address for subsequent function calls

Question

This question is closely related to this one: Why is the address of a local variable identical for different executions? . I understand the answer to that question, but if I add something on the stack between the calls to fun, the address is still the same:

int fun(int x);

int main()
{
    fun(10);
    int p = 0x12345678;
    fun(11);   
    return 0;
}

int fun(int x)
{
    int loc;//local variable
    cout<<&loc;
    return 0;
}

I expected that the variable address reported by the second call to fun to be greater with 4 bytes than the previous one, as I introduced on the stack the variable p.

My intuition says that this is a sort of compiler optimization, more specifically the memory for p is 'allocated' before it is actually defined, which goes further to the conclusion that memory is allocated (maybe I should say reserved, not allocated) for local variables at the beginning of the function.

Answer 1

Because the call stack frame is same. Variable p was allocated on stack, even before first call to fun was made. Other than this, compiler optimization play its role. You shouldn't rely on such statistics (they are seldom useful).