Set Clear Toggle a Specific Bit in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does it mean to set a specific bit in a number?

Setting a bit means changing that bit to 1, regardless of its current value.

beginner

How do you clear a specific bit in a number?

Clearing a bit means changing that bit to 0, regardless of its current value.

beginner

What does it mean to toggle a specific bit?

Toggling a bit means changing it from 0 to 1 or from 1 to 0, flipping its current value.

intermediate

Which operator is used to set a bit at position pos in C?

The bitwise OR operator (|) with a mask: num | (1 << pos) sets the bit at pos.

intermediate

How do you toggle a bit at position pos in C?

Use the bitwise XOR operator (^): num ^ (1 << pos) flips the bit at pos.

Which operation sets the 3rd bit (0-based) of number num in C?

A num ^ (1 << 3)

B num & ~(1 << 3)

C num | (1 << 3)

D num & (1 << 3)

Setting a bit uses OR (|) with a mask that has 1 at the bit position.

How do you clear the 2nd bit of num?

A num & ~(1 << 2)

B num | (1 << 2)

C num ^ (1 << 2)

D num & (1 << 2)

Clearing a bit uses AND (&) with the negated mask ~(1 << pos).

What does num ^ (1 << pos) do?

A Sets the bit at pos

B Toggles the bit at pos

C Clears the bit at pos

D Checks the bit at pos

XOR (^) flips the bit at the given position.

If num = 8 (1000 binary), what is num | (1 << 1)?

A 10 (1010 binary)

B 12 (1100 binary)

C 0 (0000 binary)

D 9 (1001 binary)

Setting bit 1 adds 2 to 8, resulting in 10 (1010 binary).

Which operator is used to clear a bit?

A Bitwise OR (|)

B Bitwise XOR (^)

C Bitwise NOT (~)

D Bitwise AND (&) with negated mask

Clearing uses AND with the negated mask to set the bit to 0.

Explain how to set, clear, and toggle a specific bit in a number using bitwise operators in C.

Think about how each operator affects bits: OR sets, AND clears, XOR flips.

Describe a real-life example where toggling a bit might be useful.

Imagine a light switch that can be flipped on or off.