Introduction to C++ Bitset

24 Sep 2023

Bitset

The std::bitset class is part of the <bitset> header and allows you to represent a fixed-size sequence of bits. This class provides various methods and operations that make it easy to perform bitwise operations, manipulate individual bits, and perform logical operations on bits.

Creating a std::bitset object is straightforward. You specify the number of bits you want to work with as a template parameter. For example, to create a std::bitset with 8 bits:

std::bitset<8> myBits;

This creates a std::bitset object named myBits with 8 bits, where each bit is initially set to 0.

To set the bits of a std::bitset object, you can use the set method and provide the index of the bit you want to set. For example, to set the third bit:

myBits.set(2); 

Now, the third bit (index 2) of myBits is set to 1.

You can also set or clear multiple bits at once using the set and reset methods with a range of indices:

myBits.set(2, 5); // Set bits from index 2 to 5 (inclusive)
myBits.reset(4, 7); // Reset bits from index 4 to 7 (inclusive)

To access individual bits, you can use the [] operator. For example, to get the value of the second bit:

bool bitValue = myBits[1];

You can perform various logical operations on std::bitset objects, such as bitwise AND (&), OR (|), XOR (^), and NOT (~). These operators allow you to combine or manipulate bits easily.

std::bitset<8> bits1(0b10101010); // 8 bits initialized with binary literal
std::bitset<8> bits2(0b11001100);

std::bitset<8> resultAnd = bits1 & bits2; // Bitwise AND operation
std::bitset<8> resultOr = bits1 | bits2; // Bitwise OR operation
std::bitset<8> resultXor = bits1 ^ bits2; // Bitwise XOR operation
std::bitset<8> resultNot = ~bits1; // Bitwise NOT operation

The std::bitset class also provides several useful methods, such as count() to count the number of set bits, all() to check if all bits are set, any() to check if any bit is set, and none() to check if no bit is set.

In conclusion, the std::bitset class in C++ provides a convenient and efficient way to work with bits. Whether you need to manipulate individual bits, perform logical operations, or count the number of set bits, std::bitset offers a comprehensive set of methods and operations to handle bits effectively.

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