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 on two integers a and b.

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 | (bitwise OR) instead of & (bitwise AND).

Using ^ (bitwise XOR) which returns 1 only if 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 a left shift by 2 bits on integer x.

DSA C

int shifted = x [1] 2;

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).

Using bitwise AND or OR operators mistakenly.

The left shift operator << moves bits to the left, effectively multiplying the number by 2 for each shift.

3fill in blank

hard

Fix the error in the code to perform bitwise NOT on variable val.

DSA C

int result = [1]val;

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

A~

B|

C&

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Using & or | which are AND and OR operators.

Using ^ which is XOR, not NOT.

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

4fill in blank

hard

Fill both blanks to create a mask that sets the 3rd bit of number num using bitwise OR.

DSA C

int mask = 1 [1] 2;
int result = num [2] mask;

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 for mask.

Using AND instead of OR to set the bit.

Shift 1 left by 2 to create a mask for the 3rd bit, then use OR | to set that bit in num.

5fill in blank

hard

Fill all three blanks to create a mask for the 1st bit, toggle the 1st bit of variable val using XOR, and isolate the 1st bit using AND.

DSA C

int mask = 1 [1] 0;
int toggled = val [2] mask;
int isolated = val [3] mask;

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

A<<

B^

C&

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using OR instead of XOR to toggle bits.

Using right shift instead of left shift for mask.

Shift 1 left by 0 to create mask for 1st bit, XOR ^ toggles the bit, AND & isolates the bit.

Practice

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

easy

A. 0

B. 1

C. 6

D. 7

Solution

1. Step 1: Convert numbers to binary

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

2. Step 2: Perform bitwise AND operation

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

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
• Mixing bit positions during calculation

2. Which of the following is the correct syntax for left shifting the integer x by 2 bits 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

   The left shift operator is written as << and shifts bits to the left.

2. Step 2: Check syntax correctness

   x << 2; uses x << 2; which correctly shifts bits of x left by 2 positions.

3. Final Answer:

   x << 2; -> Option C

4. Quick Check:

   Left shift syntax = x << 2; [OK]

Hint: Use << for left shift, >> for right shift [OK]

Common Mistakes:

• Using >>> which is invalid in C
• Confusing left shift with right shift
• Incorrect operator placement or syntax

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

int x = 6; // binary 0110
int y = x ^ 3; // 3 = 0011
printf("%d", y);

medium

A. 9

B. 7

C. 1

D. 5

Solution

1. Step 1: Convert numbers to binary and apply XOR

   6 in binary is 0110, 3 is 0011. XOR operation: 0110 ^ 0011 = 0101.

2. Step 2: Calculate decimal value of XOR result

   0101 in binary equals 5 decimal.

3. Final Answer:

   5 -> Option D

4. Quick Check:

   6 ^ 3 = 5 [OK]

Hint: XOR flips bits where bits differ [OK]

Common Mistakes:

• Mixing XOR with OR or AND
• Incorrect binary conversion
• Misreading bit positions

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

int x = 8;
int y = ~x << 1;
printf("%d", y);

medium

A. Using ~ operator without parentheses causes wrong shift

B. Missing semicolon after declaration

C. Shift operator << cannot be used with ~ operator

D. No error, code runs correctly

Solution

1. Step 1: Understand operator precedence

   The bitwise NOT (~) has higher precedence than shift (<<), so ~x is evaluated first.

2. Step 2: Check if parentheses needed

   Without parentheses, ~x is computed, then shifted left. This is correct but may cause confusion if intended differently.

3. Step 3: Identify common mistake

   If intention was to shift x first then NOT, parentheses are needed. Otherwise, no syntax error but logic may be wrong.

4. Final Answer:

   Using ~ operator without parentheses causes wrong shift -> Option A

5. Quick Check:

   Operator precedence matters; use parentheses [OK]

Hint: Use parentheses to control bitwise operation order [OK]

Common Mistakes:

• Ignoring operator precedence
• Assuming shift applies before NOT
• Thinking code has syntax error when it doesn't

5. Given an integer n, which expression correctly checks if the 3rd bit (from right, zero-based) is set (1)?

hard

A. (n & (1 << 3)) != 0

B. (n | (1 << 3)) == 0

C. (n ^ (1 << 3)) == 0

D. (n >> 3) & 1 == 0

Solution

1. Step 1: Understand bit position and mask

   The 3rd bit (zero-based) means bit at position 3. Mask is 1 shifted left by 3: (1 << 3) = 8.

2. Step 2: Check if bit is set using AND

   Using (n & (1 << 3)) checks if that bit is 1. If result is not zero, bit is set.

3. Final Answer:

   (n & (1 << 3)) != 0 -> Option A

4. Quick Check:

   Bit check uses AND with mask [OK]

Hint: Use AND with (1 << bit_position) to check bit [OK]

Common Mistakes:

• Using OR or XOR instead of AND for checking
• Wrong bit position shift
• Comparing shifted bit to zero incorrectly