Bit Manipulation Basics AND OR XOR NOT Left Right Shift in DSA Rust - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the AND (&) bitwise operator do between two bits?

The AND operator returns 1 only if both bits are 1; otherwise, it returns 0.
Example: 1 & 1 = 1, 1 & 0 = 0, 0 & 0 = 0.

beginner

Explain the OR (|) bitwise operator with an example.

The OR operator returns 1 if at least one of the bits is 1; otherwise, it returns 0.
Example: 1 | 0 = 1, 0 | 0 = 0.

beginner

What is the result of XOR (^) between two bits?

XOR returns 1 if the bits are different, and 0 if they are the same.
Example: 1 ^ 0 = 1, 1 ^ 1 = 0.

beginner

What does the NOT (~) operator do to a bit?

The NOT operator flips the bit: 0 becomes 1, and 1 becomes 0.
Example: ~1 = 0, ~0 = 1.

beginner

What is the effect of left shift (<<) and right shift (>>) operators on a number?

Left shift (<<) moves bits to the left, adding zeros on the right, effectively multiplying by 2 for each shift.
Right shift (>>) moves bits to the right, discarding bits on the right, effectively dividing by 2 for each shift.
Example: 4 << 1 = 8, 8 >> 1 = 4.

What is the result of 5 & 3 in binary? (5 = 0101, 3 = 0011)

A 0100

B 0111

C 0010

D 0001

5 (0101) & 3 (0011) = 0001 because only the last bit is 1 in both.

Which operator returns 1 only if exactly one of the bits is 1?

A XOR (^)

B AND (&)

C OR (|)

D NOT (~)

XOR returns 1 only when bits differ.

What does the expression 6 << 2 evaluate to?

A 12

B 24

C 3

D 8

Left shift by 2 multiplies 6 by 4 (2^2), so 6 << 2 = 24.

What is the binary result of ~0b1010 (4-bit)?

A 1111

B 1010

C 0101

D 0000

NOT flips bits: 1010 becomes 0101.

Which operator would you use to clear specific bits in a number?

A AND (&)

B Left Shift (<<)

C XOR (^)

D OR (|)

AND with 0 clears bits; AND with 1 keeps bits.

Describe how AND, OR, XOR, and NOT operators work on bits with simple examples.

Think about how each operator treats 0 and 1 bits.

Explain what happens when you apply left shift and right shift operators to a number.

Imagine moving digits in a number left or right.

Practice

1. What is the result of the bitwise AND operation between 0b1101 and 0b1011?

easy

A. 0b1001

B. 0b1111

C. 0b0101

D. 0b0011

Solution

1. Step 1: Understand bitwise AND operation

   Bitwise AND compares each bit of two numbers and returns 1 only if both bits are 1.

2. Step 2: Apply AND to each bit of 0b1101 and 0b1011

   Bits: 1&1=1, 1&0=0, 0&1=0, 1&1=1, so result is 0b1001.

3. Final Answer:

   0b1001 -> Option A

4. Quick Check:

   1101 & 1011 = 1001 [OK]

Hint: AND keeps bits set only if both are 1 [OK]

Common Mistakes:

• Confusing AND with OR operation
• Mixing bit positions when calculating
• Forgetting binary format in answer

2. Which of the following is the correct Rust syntax to perform a bitwise XOR between variables a and b?

easy

A. let c = a & b;

B. let c = a && b;

C. let c = a ^ b;

D. let c = a | b;

Solution

1. Step 1: Recall Rust bitwise XOR operator

   In Rust, the caret symbol (^) is used for bitwise XOR.

2. Step 2: Check each option's operator

   The options use: & (bitwise AND), && (logical AND), | (bitwise OR), ^ (bitwise XOR). Only ^ is correct.

3. Final Answer:

   let c = a ^ b; -> Option C

4. Quick Check:

   Bitwise XOR in Rust uses ^ [OK]

Hint: XOR uses ^ symbol in Rust [OK]

Common Mistakes:

• Using && instead of ^ for XOR
• Confusing bitwise OR (|) with XOR
• Using logical operators instead of bitwise

3. What is the output of the following Rust code?

let x: u8 = 0b0011_1100;
let y: u8 = 0b0000_1101;
let z = x | y;
println!("{:08b}", z);

medium

A. 00111101

B. 00110001

C. 00001101

D. 00111100

Solution

1. Step 1: Understand bitwise OR operation

   Bitwise OR returns 1 if at least one bit is 1 in either number.

2. Step 2: Apply OR to each bit of x and y

   x = 00111100, y = 00001101; OR bits: 0|0=0,0|0=0,1|0=1,1|0=1,1|1=1,1|1=1,0|0=0,0|1=1; result = 00111101.

3. Final Answer:

   00111101 -> Option A

4. Quick Check:

   00111100 | 00001101 = 00111101 [OK]

Hint: OR sets bit if either bit is 1 [OK]

Common Mistakes:

• Mixing OR with AND operation
• Misreading binary digits
• Ignoring leading zeros in output

4. Identify the error in this Rust code snippet that attempts to left shift a variable:

let a: u8 = 0b0001_0001;
let b = a << 8
println!("{:08b}", b);

medium

A. Incorrect use of << operator, should be >>

B. Shift amount exceeds variable bit size causing overflow

C. Cannot print binary format with {:08b}

D. Missing semicolon after variable declaration

Solution

1. Step 1: Check for syntax errors

   The declaration 'let b = a << 8' is missing a semicolon (;).

2. Step 2: Verify other parts

   << is correct for left shift; Rust masks large shift amounts without panic/overflow error; {:08b} works for binary output.

3. Final Answer:

   Missing semicolon after variable declaration -> Option D

4. Quick Check:

   Missing ; after let causes compile error [OK]

Hint: Rust statements must end with semicolon [OK]

Common Mistakes:

• Omitting semicolons after let statements
• Confusing left shift with right shift
• Assuming shifts panic on large amounts

5. Given a 16-bit unsigned integer num, which Rust expression correctly clears (sets to 0) the 5th bit (counting from 0 at the right) without affecting other bits?

hard

A. num | (1 << 5)

B. num & !(1 << 5)

C. num ^ (1 << 5)

D. num << 5

Solution

1. Step 1: Understand clearing a bit

   To clear a bit, use AND with a mask that has 0 at target bit and 1 elsewhere.

2. Step 2: Create mask for 5th bit

   1 << 5 creates a mask with 1 at 5th bit; negating it with ! flips bits, making 0 at 5th bit.

3. Step 3: Apply mask with AND

   num & !(1 << 5) clears 5th bit, keeps others unchanged.

4. Final Answer:

   num & !(1 << 5) -> Option B

5. Quick Check:

   Clear bit 5 using AND with inverted mask [OK]

Hint: Clear bit with AND and inverted mask [OK]

Common Mistakes:

• Using OR instead of AND to clear bits
• Using XOR which toggles bits
• Shifting num instead of mask