GATE | Gate IT 2007 | Question 34

Consider the program below in a hypothetical programming language which allows global variables and a choice of static or dynamic scoping.

int i ;
program main ()
{
    i = 10;
    call f();
}

procedure f()
{
    int i = 20;
    call g ();
}
procedure g ()
{
    print i;
}

Let x be the value printed under static scoping and y be the value printed under dynamic scoping. Then, x and y are
(A) x = 10, y = 10
(B) x = 20, y = 10
(C) x = 10, y = 20
(D) x = 20, y = 20

Answer: (C)
Explanation: Static scoping:

int i ;
program main ()
{
    i = 10;
    call f();
}

procedure f()
{
    int i = 20;
    call g ();
}
procedure g ()
{
    print i; //as i=20 is scoped only within f() so it will point to global i
}
  So, 10 is printed
Dynamic scoping:
int i ;
program main ()
{
    i = 10;
    call f();
}

procedure f()
{
    int i = 20; // here global scoped i is changed
    call g ();
}
procedure g ()
{
    print i; // global value changed so, i=20 printed
}

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