GATE | GATE-CS-2015 (Set 1) | Question 21

The output of the following C program is __________.

void f1 (int a, int b)
{
  int c;
  c=a; a=b; b=c;
}
void f2 (int *a, int *b)
{
  int c;
  c=*a; *a=*b;*b=c;
}
int main()
{
  int a=4, b=5, c=6;
  f1(a, b);
  f2(&b, &c);
  printf (“%d”, c-a-b);
  return 0;
}

(A) -5
(B) -4
(C) 5
(D) 3

Answer: (A)
Explanation: The function call to to f1(a, b) won’t have any effect as the values are passed by value.

The function call f2(&b, &c) swaps values of b and c. So b becomes 6 and c becomes 5. Value of c-a-b becomes 5-4-6 which is -5.
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