C | Storage Classes and Type Qualifiers | Question 18

Output of following program

#include <stdio.h>
int fun(int n)
{
    static int s = 0;
    s = s + n;
    return (s);
}

int main()
{
    int i = 10, x;
    while (i > 0)
    {
        x = fun(i);
        i--;
    }
    printf ("%d ", x);
    return 0;
}

(A) 0
(B) 100
(C) 110
(D) 55

Answer: (D)
Explanation: Since s is static, different values of i are added to it one by one.

So final value of s is

s = i + (i-1) + (i-2) + … 3 + 2 + 1.

The value of s is i*(i+1)/2. For i = 10, s is 55.
Quiz of this Question