Last Updated : 18 Dec, 2018

What will be the output of the C program given below.

#include
int cal(int n, int *p) {
int t, f;
if (n <= 2) { *p = 1; return 1; } t = cal(n-1, p); f = t + *p; *p = t; return f; } int main() { int x = 6; printf(\"%d\", cal(x, &x)); return 0; } [/sourcecode]

(A) 4
(B) 6
(C) 7
(D) 8


Answer: (D)

Explanation: x=6 and let &x=1000

cal(6,1000)
                 t=5, f=5 +3=8
                 *p=t=5
                 Return 8
cal(5,1000)
                 t=3, f=3 + 2=5
                 *p=t=3
                 Return 5
cal(4,1000)
                 t=2, f=2+1=3
                 *p=t=2
                 Return 3
cal(3,1000)
                 t=1,f=1+1=2
                 *p=t=1 
                 Return 2
cal(2,1000)
                 *p=1
                 Return 1

So, option (D) is correct.


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