UPPCL AE 2018:75

Question

What is the output of the following $\text{C}$ program?

#include<stdio.h>

int main(void) {
    struct bitfields  {
        int bits_1 : 2;
        int bits_2 : 4;
        int bits_3 : 4;
        int bits_4 : 3;
        } bit = {2, 3, 8, 7};
        printf(“%d %d %d %d”, bit.bits_1, bit.bits_2, bit.bits_3, bit.bits_4 );
}

• A. $\text{-}2 \; 3 \; \text{-}8 \; \text{-}1 $
• B. $2 \; 4 \; 4 \; 3 $
• C. $0 \; 0 \; 0 \; 0 $
• D. $2 \; 3 \; 8 \; 7 $

Answer 1

1. bits_1 is a 2-bit field. The value assigned is 2, which is represented as 10 in binary.

2. bits_2 is a 4-bit field. The value assigned is 3, which is represented as 0011 in binary.

3. bits_3 is another 4-bit field. The value assigned is 8, which is represented as 1000 in binary. However, in a 4-bit signed integer representation (assuming 2's complement), 1000 is interpreted as -8.

4. bits_4 is a 3-bit field. The value assigned is 7, which is represented as 111 in binary. In a 3-bit signed integer representation, 111 is interpreted as -1.

Putting it all together, the binary representations are:

• bits_1: 10 (-2 in decimal)
• bits_2: 0011 (3 in decimal)
• bits_3: 1000 (-8 in decimal)
• bits_4: 111 (-1 in decimal)