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

Practice - 5 Tasks

1fill in blank

easy

Complete the code to perform bitwise AND of two integers a and b.

DSA Java

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 & will perform OR operation.

Using ^ will perform XOR, which is different.

Using ~ is bitwise NOT, which is unary.

The bitwise AND operator is &. It 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 integers x and y.

DSA Java

int combined = x [1] y;

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

A^

B&

C|

D~

Attempts:

3 left

💡 Hint

Common Mistakes

Using & will perform AND, not OR.

Using ^ will perform XOR.

Using ~ is NOT operator, unary.

The bitwise OR operator is |. It returns 1 if either bit is 1.

3fill in blank

hard

Fix the error in the code to perform bitwise XOR of two integers m and n.

DSA Java

int xorResult = m [1] n;

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

A^

B|

C&

D~

Attempts:

3 left

💡 Hint

Common Mistakes

Using & or | instead of ^.

Using ~ which is NOT operator.

The bitwise XOR operator is ^. It returns 1 only if bits are different.

4fill in blank

hard

Fill both blanks to perform left shift of integer val by 3 bits and then bitwise NOT the result.

DSA Java

int shifted = val [1] 3;
int result = [2]shifted;

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

A<<

B~

C>>

D>>>

Attempts:

3 left

💡 Hint

Common Mistakes

Using >> or >>> instead of << for left shift.

Using ~ after val instead of after shifted.

Left shift operator is <<. Bitwise NOT operator is ~.

5fill in blank

hard

Fill all three blanks to perform right shift of number num by 2 bits, then bitwise AND with mask, and finally bitwise OR with flag.

DSA Java

int shifted = num [1] 2;
int masked = shifted [2] mask;
int result = masked [3] flag;

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

A>>

B&

C|

D<<

Attempts:

3 left

💡 Hint

Common Mistakes

Using << instead of >> for right shift.

Mixing AND and OR operators.

The right shift operator is >> (signed right shift) or >>> (unsigned right shift). In the options, >> is provided (option A). Bitwise AND is &, bitwise OR is |.

Practice

1. What does the bitwise AND operator (&) do when applied to two bits?

easy

A. Flips the bits from 0 to 1 and 1 to 0

B. Returns 1 if at least one bit is 1

C. Returns 1 only if both bits are 1

D. Returns 0 only if both bits are 0

Solution

1. Step 1: Understand bitwise AND operation

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

2. Step 2: Apply to example bits

   For bits 1 & 1, result is 1; for 1 & 0 or 0 & 1 or 0 & 0, result is 0.

3. Final Answer:

   Returns 1 only if both bits are 1 -> Option C

4. Quick Check:

   AND = 1 only if both bits 1 [OK]

Hint: AND returns 1 only when both bits are 1 [OK]

Common Mistakes:

• Confusing AND with OR operator
• Thinking AND flips bits
• Assuming AND returns 1 if any bit is 1

2. Which of the following is the correct syntax for left shifting an integer variable x by 3 positions in Java?

easy

A. x << 3;

B. x >> 3;

C. x <<< 3;

D. x >>> 3;

Solution

1. Step 1: Recall left shift operator syntax in Java

   Left shift operator is << and shifts bits to the left.

2. Step 2: Identify correct usage

   To shift variable x left by 3 bits, use x << 3;. Other options are right shifts or invalid.

3. Final Answer:

   x << 3; -> Option A

4. Quick Check:

   Left shift = x << number [OK]

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

Common Mistakes:

• Using >>> for left shift (it's unsigned right shift)
• Using <<< which is invalid syntax
• Confusing left and right shift operators

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

int a = 5;  // binary 0101
int b = 3;  // binary 0011
int c = a ^ b;
System.out.println(c);

medium

A. 8

B. 7

C. 2

D. 6

Solution

1. Step 1: Convert numbers to binary

   a = 5 is 0101, b = 3 is 0011 in binary.

2. Step 2: Apply XOR operation bitwise

   XOR returns 1 if bits differ, 0 if same.
   0101 XOR 0011 = 0110 (binary) which is 6 decimal.

3. Final Answer:

   6 -> Option D

4. Quick Check:

   5 ^ 3 = 6 [OK]

Hint: XOR sets bits where inputs differ [OK]

Common Mistakes:

• Confusing XOR with OR or AND
• Calculating XOR incorrectly bitwise
• Assuming XOR adds numbers

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

int x = 8;
int y = ~x << 2;
System.out.println(y);

medium

A. No error; the code runs and prints a valid integer

B. The shift operator << must be used before the NOT operator ~

C. The bitwise NOT operator (~) cannot be used on integers

D. The variable y should be declared as long instead of int

Solution

1. Step 1: Analyze bitwise NOT and shift usage

   The NOT operator (~) flips all bits of x. Then the result is shifted left by 2 bits.

2. Step 2: Check Java syntax and types

   Both ~ and << operators work on int type. The expression is valid and prints an integer.

3. Final Answer:

   No error; the code runs and prints a valid integer -> Option A

4. Quick Check:

   ~ and << valid on int [OK]

Hint: Bitwise NOT and shifts work fine on int in Java [OK]

Common Mistakes:

• Thinking ~ cannot be used on int
• Assuming operator order is wrong
• Believing int can't hold shifted values

5. Given an integer n, which expression correctly toggles (flips) the 4th bit (counting from 0) of n using bitwise operators in Java?

hard

A. n = n | (1 << 4);

B. n = n ^ (1 << 4);

C. n = n & ~(1 << 4);

D. n = ~n << 4;

Solution

1. Step 1: Understand toggling a bit

   Toggling means flipping the bit: 0 becomes 1, 1 becomes 0.

2. Step 2: Identify correct operator for toggling

   XOR (^) with 1 at the bit position flips that bit. So n ^ (1 << 4) toggles the 4th bit.

3. Final Answer:

   n = n ^ (1 << 4); -> Option B

4. Quick Check:

   Toggling bit uses XOR with mask [OK]

Hint: Use XOR with mask to toggle bits [OK]

Common Mistakes:

• Using OR to toggle (only sets bit)
• Using AND with negation to toggle (clears bit)
• Using NOT and shift incorrectly