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

Practice - 5 Tasks

1fill in blank

easy

Complete the code to perform bitwise AND of two numbers.

DSA C++

int 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 '|' instead of '&' for AND operation.

Using '^' which is XOR, not AND.

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 C++

int 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 '&' instead of '|' for OR operation.

Confusing OR with XOR '^'.

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 correctly perform bitwise NOT on a number.

DSA C++

int result = [1]num;

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

A~

B|

C&

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Using '^' which is XOR, not NOT.

Using '&' or '|' which are AND/OR operators.

The bitwise NOT operator '~' flips all bits of the number.

4fill in blank

hard

Fill both blanks to shift bits left by 2 positions and then right by 1 position.

DSA C++

int shifted = (value [1] 2) [2] 1;

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

A<<

B>>

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' or '-' instead of shift operators.

Reversing the order of shifts.

Left shift '<<' moves bits to the left, multiplying by 2 for each shift. Right shift '>>' moves bits to the right, dividing by 2 for each shift.

5fill in blank

hard

Fill all three blanks to create a mask that sets the 3rd bit (from right, zero-based) of number n.

DSA C++

int mask = 1 [1] 3;
int result = n [2] mask;
int cleared = n [3] mask;

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

A<<

B|

C&~

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Using '^' instead of '&~' to clear bit.

Not shifting 1 to correct bit position.

Shift 1 left by 3 to create mask. Use OR '|' to set the bit. Use AND with NOT '&~' to clear the bit.

Practice

1. What is the result of the bitwise AND operation between 5 and 3? (In binary, 5 = 0101, 3 = 0011)

easy

A. 0

B. 1

C. 6

D. 7

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 AND 0011 = 0001 (only bits where both are 1 remain 1).

3. Final Answer:

   1 -> Option B

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 decimal to binary correctly
• Assuming bitwise AND adds numbers

2. Which of the following is the correct syntax for performing a left shift by 2 bits on an integer variable x in C++?

easy

A. x << 2;

B. x >> 2;

C. x <<< 2;

D. x >> 2 <<;

Solution

1. Step 1: Understand left shift operator

   In C++, left shift is done using << operator.

2. Step 2: Check syntax correctness

   x << 2; uses x << 2; which is correct syntax for left shift by 2 bits.

3. Final Answer:

   x << 2; -> Option A

4. Quick Check:

   Left shift uses << operator [OK]

Hint: Left shift uses <<, right shift uses >> [OK]

Common Mistakes:

• Using >>> which is not valid in C++
• Confusing left shift with right shift
• Adding extra symbols after operator

3. What is the output of the following C++ code?

int x = 12;  // binary 1100
int y = 5;   // binary 0101
int z = x ^ y;
std::cout << z << std::endl;

medium

A. 8

B. 15

C. 9

D. 7

Solution

1. Step 1: Convert numbers to binary

   x = 12 (1100), y = 5 (0101).

2. Step 2: Perform bitwise XOR

   1100 XOR 0101 = 1001 (bits differ become 1).

3. Step 3: Convert result back to decimal

   1001 in decimal is 9.

4. Final Answer:

   9 -> Option C

5. Quick Check:

   12 ^ 5 = 9 [OK]

Hint: XOR sets bits where inputs differ [OK]

Common Mistakes:

• Mixing XOR with OR or AND
• Not converting binary to decimal correctly
• Assuming XOR adds numbers

4. Identify the error in the following C++ code snippet:

int a = 8;
int b = a >> 2;
int c = ~b;
std::cout << c << std::endl;

medium

A. No error; code runs and prints the result

B. Using bitwise NOT (~) on an integer is invalid

C. Right shift operator (>>) is used incorrectly

D. Missing semicolon after variable declaration

Solution

1. Step 1: Check each operation

   Right shift (>>) on integer 8 by 2 bits is valid: 8 (1000) >> 2 = 2 (0010).

2. Step 2: Check bitwise NOT usage

   Bitwise NOT (~) on integer 2 flips bits; this is valid in C++.

3. Step 3: Verify syntax

   All semicolons are present; code compiles and runs.

4. Final Answer:

   No error; code runs and prints the result -> Option A

5. Quick Check:

   Bitwise NOT and shifts are valid [OK]

Hint: Bitwise NOT and shifts are valid on integers [OK]

Common Mistakes:

• Thinking ~ is invalid on integers
• Confusing shift direction
• Assuming missing semicolon without checking

5. Given an integer n = 29, which of the following expressions correctly clears (sets to 0) the 3rd bit (counting from 0, right to left) using bit manipulation?

hard

A. ~n & (1 << 3)

B. n | (1 << 3)

C. n ^ (1 << 3)

D. n & ~(1 << 3)

Solution

1. Step 1: Understand clearing a bit

   To clear a bit, use AND with NOT mask that has 1 at target bit.

2. Step 2: Analyze each option

   n & ~(1 << 3): n & ~(1 << 3) clears 3rd bit correctly.
   n | (1 << 3): n | (1 << 3) sets 3rd bit.
   n ^ (1 << 3): n ^ (1 << 3) toggles 3rd bit.
   ~n & (1 << 3): ~n & (1 << 3) isolates 3rd bit of inverted n, not clearing.

3. Final Answer:

   n & ~(1 << 3) -> Option D

4. Quick Check:

   Clear bit = AND with NOT mask [OK]

Hint: Clear bit: AND with NOT of bit mask [OK]

Common Mistakes:

• Using OR instead of AND to clear bits
• Confusing toggle (XOR) with clear
• Misunderstanding bit indexing