C Programming - C Bitwise Operators

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C Programming - C Bitwise Operators

C Bitwise Operators

Bitwise operators in C perform operations directly on the binary representations of integers. These operators manipulate individual bits of data, making them highly efficient for low-level programming, such as embedded systems, hardware interfacing, and performance-critical applications.

List of Bitwise Operators

Key Characteristics

1. Bitwise AND (&):
• Compares each bit of the operands and sets the corresponding bit in the result to 1 only if both bits are 1.

int a = 12, b = 10; // a = 1100, b = 1010
int result = a & b; // result = 1000 (8 in decimal)

1. Bitwise OR (|):
• Compares each bit of the operands and sets the corresponding bit in the result to 1 if at least one bit is 1.

int a = 12, b = 10; // a = 1100, b = 1010
int result = a | b; // result = 1110 (14 in decimal)

1. Bitwise XOR (^):
• Compares each bit of the operands and sets the corresponding bit in the result to 1 if the bits are different.

int a = 12, b = 10; // a = 1100, b = 1010
int result = a ^ b; // result = 0110 (6 in decimal)

1. Bitwise NOT (~):
• Inverts all bits (flips 1 to 0 and 0 to 1).

int a = 12;         // a = 1100
int result = ~a;    // result = 0011 (in 2's complement: -13 in decimal)

1. Left Shift (<<):
• Shifts the bits of the operand to the left by the specified number of positions. The vacant bits on the right are filled with 0.

int a = 3;          // a = 0011
int result = a << 2; // result = 1100 (12 in decimal)

1. Right Shift (>>):
• Shifts the bits of the operand to the right by the specified number of positions. The vacant bits on the left depend on the type of shift (logical or arithmetic).

int a = 12;         // a = 1100
int result = a >> 2; // result = 0011 (3 in decimal)

Example Program

#include <stdio.h>
 
int main() {
    int a = 12, b = 10;
 
    printf("a & b = %d\n", a & b);  // Bitwise AND
    printf("a | b = %d\n", a | b);  // Bitwise OR
    printf("a ^ b = %d\n", a ^ b);  // Bitwise XOR
    printf("~a = %d\n", ~a);        // Bitwise NOT
    printf("a << 2 = %d\n", a << 2); // Left Shift
    printf("a >> 2 = %d\n", a >> 2); // Right Shift
 
    return 0;
}

Output:

a & b = 8
a | b = 14
a ^ b = 6
~a = -13
a << 2 = 48
a >> 2 = 3

Applications of Bitwise Operators

1. Masking Bits:
• Used to extract specific bits from a binary number.

int num = 0b10101010;
int mask = 0b00001111;
int result = num & mask; // Extracts the lower 4 bits

1. Setting/Clearing Specific Bits:
• Set a bit: num | (1 << n)
• Clear a bit: num & ~(1 << n)

int num = 0b10101010;
num |= (1 << 3);  // Set the 4th bit
num &= ~(1 << 2); // Clear the 3rd bit

1. Toggling Bits:
• Flip specific bits using XOR.

int num = 0b10101010;
num ^= (1 << 3); // Toggle the 4th bit

1. Checking Specific Bits:
• Check if a bit is set: (num & (1 << n)) != 0

int num = 0b10101010;
if (num & (1 << 3)) {
    printf("4th bit is set\n");
}

1. Efficient Multiplication/Division:
• Multiply by 2^n: num << n
• Divide by 2^n: num >> n

int num = 5;
int result = num << 3; // Multiplies num by 8

Points to Remember

1. Bitwise operations are performed on integers only.
2. Be cautious with signed integers during shifts, as results may vary.
3. Use parentheses for clarity in complex expressions involving bitwise operators.
4. Use bitwise operators in scenarios requiring performance-critical optimizations.