Bit manipulation techniques - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of bitwise AND operation

What is the output of the following C code?

C

int a = 12;  // binary: 1100
int b = 10;  // binary: 1010
int c = a & b;
printf("%d", c);

A 8

B 14

C 2

D 10

💡 Hint

Remember that & compares bits and returns 1 only if both bits are 1.

12 in binary is 1100 and 10 is 1010. Bitwise AND gives 1000 which is 8 in decimal.

❓ Predict Output

intermediate

Output of left shift operation

What will be printed by this C code?

C

unsigned int x = 5;  // binary: 0000 0101
unsigned int y = x << 2;
printf("%u", y);

A 10

B 2

C 20

D 40

💡 Hint

Left shift by 2 means multiply by 2 twice (4 times).

5 shifted left by 2 bits is 5 * 4 = 20.

❓ Predict Output

advanced

Output of toggling bits using XOR

What is the output of this C code snippet?

C

int num = 29;  // binary: 0001 1101
int mask = 15; // binary: 0000 1111
int result = num ^ mask;
printf("%d", result);

A 18

B 14

C 12

D 31

💡 Hint

XOR flips bits where mask has 1s.

29 (00011101) XOR 15 (00001111) flips last 4 bits: 00010010 which is 18 decimal.

❓ Predict Output

advanced

Output of checking if a number is a power of two

What does this C code print?

C

int n = 16;
int check = (n & (n - 1)) == 0;
printf("%d", check);

A 16

B 0

C 1

D 15

💡 Hint

A power of two has only one bit set.

For powers of two, n & (n-1) equals zero, so check is 1 (true).

❓ Predict Output

expert

Output of clearing the rightmost set bit

What is the output of this C code?

C

int x = 44;  // binary: 0010 1100
int y = x & (x - 1);
printf("%d", y);

A 44

B 40

C 12

D 32

💡 Hint

x & (x-1) clears the rightmost set bit.

44 in binary is 00101100. Clearing rightmost set bit gives 00101000 which is 40.