What is the output of the following C program? #include int main(void) { int a = 7, b = 12; a ^= b; b ^= a; a ^= b; printf("%d %d\n", a, b); return 0; }

Bitwise Operators · Predict the Output · Question 5

XOR swap without a temporary – output Answer, explanation & discussion

Output
Easy
0 comments
Answer explained
Moderated community

Question 5 Back to Exercise

What is the output of the following C program?

main.c

#include <stdio.h>

int main(void) {
    int a = 7, b = 12;
    a ^= b;
    b ^= a;
    a ^= b;
    printf("%d %d\n", a, b);
    return 0;
}

A 12 7 Correct
B 7 12
C 11 11
D 0 0

Correct Answer: Option A

After the first line a holds a ^ b. Then b ^= a gives b ^ (a ^ b) = a, and a ^= b gives (a ^ b) ^ a = b. The values are swapped. (It breaks if both names refer to the same variable.)

Output Integer promotion with ~ on an unsigned char – output
Output Extracting nibbles and bytes with shifts and masks
Output Power-of-two check n & (n - 1) – output
Output Toggling letter case with ^= 32 – output
Output Right-shifting a negative number with GCC/Clang
Output C23 binary literals with &, | and ^ – output

Discussion & Comments 0

Share your method, a shortcut, or ask about a step you didn't follow.

No comments yet. Be the first to share your solution!

XOR swap without a temporary – output Answer, explanation & discussion

More Bitwise Operators practice questions

Discussion & Comments 0

Post your comment