Bit Manipulation Basics AND OR XOR NOT Left Right Shift in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to perform bitwise AND of two numbers.

DSA Javascript

const result = a [1] b;

Drag options to blanks, or click blank then click option'

A^

B|

C~

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using OR operator | instead of AND.

Using XOR ^ which returns 1 when bits differ.

The bitwise AND operator & compares each bit of two numbers and returns 1 only if both bits are 1.

2fill in blank

medium

Complete the code to perform bitwise OR of two numbers.

DSA Javascript

const result = x [1] y;

Drag options to blanks, or click blank then click option'

A|

B>>

C^

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using AND & instead of OR.

Using right shift >> which shifts bits.

The bitwise OR operator | compares each bit of two numbers and returns 1 if at least one bit is 1.

3fill in blank

hard

Fix the error in the code to perform bitwise XOR of two numbers.

DSA Javascript

const result = num1 [1] num2;

Drag options to blanks, or click blank then click option'

A~

B|

C^

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using OR | or AND & instead of XOR.

Using NOT ~ which flips bits.

The bitwise XOR operator ^ returns 1 only when the bits are different.

4fill in blank

hard

Fill both blanks to perform left shift by 3 bits and then bitwise NOT.

DSA Javascript

const shifted = value [1] 3;
const result = [2]shifted;

Drag options to blanks, or click blank then click option'

A<<

B~

C>>

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using right shift >> instead of left shift.

Placing NOT operator after the value.

Left shift operator << moves bits to the left by given positions. Bitwise NOT ~ flips all bits.

5fill in blank

hard

Fill all three blanks to perform right shift by 2 bits, then bitwise AND with mask 15, and finally bitwise OR with 8.

DSA Javascript

const shifted = num [1] 2;
const masked = shifted [2] 15;
const result = masked [3] 8;

Drag options to blanks, or click blank then click option'

A>>

B&

C|

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Using left shift << instead of right shift.

Using XOR ^ instead of OR.

Right shift >> moves bits right. Bitwise AND & masks bits. Bitwise OR | sets bits.

Practice

1. What is the result of the bitwise AND operation between 5 and 3? (5 & 3)

easy

A. 1

B. 7

C. 0

D. 8

Solution

1. Step 1: Convert numbers to binary

   5 in binary is 0101, 3 in binary is 0011.

2. Step 2: Perform bitwise AND

   0101 & 0011 = 0001 (only bits set in both numbers remain set).

3. Final Answer:

   1 -> Option A

4. Quick Check:

   5 & 3 = 1 [OK]

Hint: AND keeps bits set in both numbers only [OK]

Common Mistakes:

• Confusing AND with OR operation
• Not converting numbers to binary before operation
• Assuming decimal addition instead of bitwise

2. Which of the following is the correct syntax for performing a bitwise XOR operation between variables a and b in JavaScript?

easy

A. let result = a | b;

B. let result = a && b;

C. let result = a % b;

D. let result = a ^ b;

Solution

1. Step 1: Identify bitwise XOR operator in JavaScript

   The XOR operator is represented by the caret symbol (^).

2. Step 2: Check syntax correctness

   let result = a ^ b; uses a ^ b, which is the correct syntax for bitwise XOR.

3. Final Answer:

   let result = a ^ b; -> Option D

4. Quick Check:

   XOR operator is ^ in JavaScript [OK]

Hint: XOR uses ^ symbol in JavaScript [OK]

Common Mistakes:

• Using && which is logical AND, not bitwise
• Using | which is bitwise OR, not XOR
• Using % which is modulo, unrelated to bits

3. What will be the output of the following JavaScript code?

let x = 8; // binary 1000
let y = x >> 2;
console.log(y);

medium

A. 2

B. 4

C. 1

D. 0

Solution

1. Step 1: Understand right shift operation

   Right shift by 2 means move bits 2 places to the right, dropping the rightmost bits.

2. Step 2: Apply right shift on binary 1000

   1000 >> 2 becomes 0010, which is decimal 2.

3. Final Answer:

   2 -> Option A

4. Quick Check:

   8 >> 2 = 2 [OK]

Hint: Right shift divides by 2 for each shift [OK]

Common Mistakes:

• Confusing right shift with left shift
• Not converting binary to decimal after shift
• Assuming shift adds zeros on left without dropping bits

4. Find the error in the following code snippet that attempts to flip all bits of a number n using bitwise NOT:

let n = 5;
let flipped = ~n;
console.log(flipped);

What is the issue?

medium

A. Missing parentheses around ~n

B. Bitwise NOT returns a negative number due to two's complement representation

C. Variable n must be a string for bitwise NOT

D. Bitwise NOT operator (~) is not supported in JavaScript

Solution

1. Step 1: Understand bitwise NOT in JavaScript

   Bitwise NOT flips all bits and returns the two's complement negative number.

2. Step 2: Explain why output is negative

   For 5 (00000101), ~5 flips bits to 11111010 which is -6 in two's complement.

3. Final Answer:

   Bitwise NOT returns a negative number due to two's complement representation -> Option B

4. Quick Check:

   ~n flips bits and returns negative number [OK]

Hint: Bitwise NOT flips bits and returns negative in JS [OK]

Common Mistakes:

• Expecting positive flipped bits as output
• Thinking ~ is unsupported operator
• Assuming input must be string for bitwise ops

5. You want to set the 3rd bit (0-indexed from right) of a number num to 1 without changing other bits. Which expression correctly does this in JavaScript?

hard

A. num = num ^ (1 << 3);

B. num = num & (1 << 3);

C. num = num | (1 << 3);

D. num = num << 3;

Solution

1. Step 1: Understand setting a bit using OR and shift

   Left shift 1 by 3 gives 00001000, which targets the 3rd bit.

2. Step 2: Use OR to set the bit without changing others

   OR with this mask sets the 3rd bit to 1, keeping others unchanged.

3. Final Answer:

   num = num | (1 << 3); -> Option C

4. Quick Check:

   Use OR with shifted 1 to set bit [OK]

Hint: Use OR with (1 << bit_position) to set bit [OK]

Common Mistakes:

• Using AND which clears bits instead of setting
• Using XOR which toggles bits and may unset
• Using left shift alone which changes number value