GATE EXAM PREPARATION IN "C" - Storage Classes and Type Qualifiers

#include <stdio.h>
int fun()
{
  static int num = 16;
  return num--;
}

int main()
{
  for(fun(); fun(); fun())
    printf("%d ", fun());
  return 0;
}

(A) Infinite loop
(B) 13 10 7 4 1
(C) 14 11 8 5 2
(D) 15 12 8 5 2


Answer: (C)

Explanation: Since num is static in fun(), the old value of num is preserved for subsequent functions calls. Also, since the statement return num– is postfix, it returns the old value of num, and updates the value for next function call.

fun() called first time: num = 16 // for loop initialization done;


In test condition, compiler checks for non zero value

fun() called again : num = 15

printf("%d \n", fun());:num=14 ->printed

Increment/decrement condition check

fun(); called again : num = 13

----------------

fun() called second time: num: 13

In test condition,compiler checks for non zero value

fun() called again : num = 12

printf("%d \n", fun());:num=11 ->printed

fun(); called again : num = 10

--------

fun() called second time : num = 10

In test condition,compiler checks for non zero value

fun() called again : num = 9

printf("%d \n", fun());:num=8 ->printed

fun(); called again   : num = 7

--------------------------------

fun() called second time: num = 7

In test condition,compiler checks for non zero value

fun() called again : num = 6

printf("%d \n", fun());:num=5 ->printed

fun(); called again   : num = 4

-----------

fun() called second time: num: 4

In test condition,compiler checks for non zero value

fun() called again : num = 3

printf("%d \n", fun());:num=2 ->printed

fun(); called again   : num = 1

----------

fun() called second time: num: 1

In test condition,compiler checks for non zero value

fun() called again : num = 0 => STOP