GATE CSE 2010 | Question: 35

Question

What is the value printed by the following C program?

#include<stdio.h>

int f(int *a, int n)
{
    if (n <= 0) return 0;
    else if (*a % 2 == 0) return *a+f(a+1, n-1);
    else return *a - f(a+1, n-1);
}

int main()
{
    int a[] = {12, 7, 13, 4, 11, 6};
    printf("%d", f(a, 6));
    return 0;
}

• A. $-9$
• B. $5$
• C. $15$
• D. $19$

Comments

@kenzou, The program won't compile with parenthesis used in the initializer. Please change it to "{ }"

---

Fixed now.

Answer 1

Suppose $int$ array takes $4$ bytes for each element and stored at base address $100$.

Follow below image. Red color shows the return value.

So, $15$ is the answer.

Correct Answer: $C$

Comments

In C leaglly it is possible to have 2 byte for "int". But there does not make any sense to have an int value which cannot go beyond $2^{16}-1 = 65535 .$ So, please assume 4 bytes whenever we use int in C. Using 2 bytes for int is like making fun of C :(

---

Thanks a lot @arjun sir . I will keep this in my mind in future. I will update this IMG tomorrow.n

Edited @Arjun Sir

---

Follow below image. Red color shows the return value.

There is no image in the answer.

---

@ Arjun Sir,

there does not make any sense to have an int value which cannot go beyond  31267

 isn’t it cannot go beyond 32767.

we have 2 bytes means,

= 2*8 (16 bits)

so from 16 bits we can have range from-   $- 2^{n-1}$   to  $+2^{n-1}$ -1 

So it’s value will be ,   -32768 to  +32767

Anyone correct me if i’m wrong..or missing something

---

@Arjun Sir but in C language size of int is compiler dependent. 

---

Does that matter here?

---

No @Arjun Sir but in general it matters right like of a question if asked that what is the size of int data type in C language ??

---

@abir_banerjee Such a question will never be asked for sure.

Answer 2

It will print
$12 + ( 7 - (13 - (4 + (11 - ( 6 + 0)))))$
$\quad = 12 + (7 - (13 - ( 4 + ( 11 -6)))))$
$\quad= 12 + 7 - 13 + 9$
$\quad= 15$

Comments

@gatecse sir can u pls tell me how this addition and subtraction works here i am not getting

---

@pavansan 
add or sub which are present inside the parathesis, do this layer by layer

eg : 6+0 is done first and then 11 - 6  and then ...

Answer 3

Answer : Option C) 15

Comments

nice  explaination

Answer 4

it is C. 15.

Answer 5

Here is the explanation !!