C++ Misc - Bit Manipulation

Bit manipulation is a programming technique that involves performing operations on individual bits or groups of bits within a binary representation of a number.

Syntax

Bit manipulation in C++ involves using bitwise operators such as:

• & - bitwise AND
• | - bitwise OR
• ^ - bitwise XOR
• ~ - bitwise NOT
• << - left shift
• >> - right shift

int a = 0b00101011; // binary literal
int b = 0b11010100;

int c = a & b; // bitwise AND
int d = a | b; // bitwise OR
int e = a ^ b; // bitwise XOR
int f = ~a;    // bitwise NOT

int g = a << 2; // left shift
int h = b >> 3; // right shift

Example

Let's say we want to set the third bit of a number to 1.

int number = 0b00001010;
number |= (1 << 2);

This code uses the bitwise OR (|) operator to set the third bit to 1. The 1 << 2 expression is a left shift that moves the 1 to the third bit position.

Output

number: 0b00001010
number: 0b00001110

Explanation

In the example above, we start with the binary number 0b00001010 which is 10 in decimal. We use the bitwise OR operator (|) to set the third bit to 1, resulting in the binary number 0b00001110, which is 14 in decimal.

Use

Bit manipulation can be used in various applications, such as:

• Setting, clearing, and toggling individual bits in a bitfield.
• Implementing efficient algorithms for tasks such as sorting and searching.
• Optimizing code for size, speed, or other factors.
• Implementing low-level protocols and hardware interfaces.

Important Points

• Bit manipulation involves performing operations on individual bits or groups of bits within a number.
• Bitwise operators such as &, |, ^, ~, <<, and >> are used for bit manipulation.
• Bit manipulation can be used for various applications such as bitfields, algorithms, optimization, and low-level interfaces.

Summary

Bit manipulation is a useful programming technique that allows us to operate on individual bits or groups of bits within a binary representation of a number. C++ provides bitwise operators such as &, |, ^, ~, <<, and >> for performing bit manipulation. Bit manipulation can be used for various applications such as bitfields, algorithms, optimization, and low-level interfaces.