C++ Library - <bitset>-alljchome-开发者的教程家园

The C Standard Library

The C Standard Library

The C++ Standard Library

The C++ STL Library

C++ Programming Resources

Selected Reading

C++ Library - <bitset>

Introduction

Bitset represents a fixed-size sequence of N bits and stores values either 0 or 1. Zero means value is false or bit is unset and one means value is true or bit is set. Bitset class emulates space efficient array of boolean values, where each element occupies only one bit.

As it emulates array, its index also starts from 0^th position. Inspanidual bit from bitset can be accessed using subscript operator. For instance to access first element of bitset foo use foo[0].

Bitset class provides constructors to create bitset from integer as well as from strings. The size of the bitset is fixed at compile time. STL provides vector<bool> class that provides dynamic resize functionapty.

Definition

Below is definition of std::bitset from <bitset> header file

template <size_t N> class bitset;

Parameters

N − Size of the bitset.

Member types

Following member types can be used as parameters or return type by member functions.

Sr.No.	Member types	Definition
1	reference	Proxy class that represents a reference to a bit.

Functions from <bitset>

Below is pst of all methods from <bitset> header.

Constructors

Sr.No.	Method & Description
1	bitset::bitset() Constructs bitset container and initiapze it with zero.
2	bitset::bitset() Constructs bitset container and initiapze it with the bit value of `val`.
3	bitset::bitset() Constructs and initiapzes a bitset container from C++ string object.
4	bitset::bitset() Constructs and initiapzes a bitset container from c-style string.

Member class

Sr.No.	Method & Description
1	bitset::reference() This is embedded class which provides l-value that can be returned from `std::bitset::operator[]`.

Bitset operators

Sr.No.	Method & Description
1	bitset::operator&= Performs bitwise AND operation on current bitset object.
2	bitset::operator\|= Performs bitwise OR operation on current bitset object.
3	bitset::operator^= Performs bitwise XOR operation on current bitset object.
4	bitset::operator<<= Performs bitwise left SHIFT operation on current bitset object.
5	bitset::operator>>= Performs bitwise right SHIFT operation on current bitset object.
6	bitset::operator~ Performs bitwise NOT operation on bitset.
7	bitset::operator<< Performs bitwise left SHIFT operation on bitset.
8	bitset::operator>> Performs bitwise right SHIFT operation on bitset.
9	bitset::operator== Test whether two bitsets are equal or not.
10	bitset::operator!= Test whether two bitsets are equal or not.
11	bitset::operator& Performs bitwise AND operation on bitset.
12	bitset::operator\| Performs bitwise OR operation on bitset.
13	bitset::operator^ Performs bitwise XOR operation on bitset.
14	bitset::operator>> Extracts upto `N` bits from `is` and stores into another bitset `x`.
15	bitset::operator>> Inserts bitset `x` to the character stream `os`.

Member functions

Sr.No.	Method & Description
1	bitset::all() Tests whether all bits from bitset are set or not.
2	bitset::any() Tests whether at least one bit from bitset is set or not.
3	bitset::count() Count number of set bits from bitset.
4	bitset::fpp() `all bits` Toggles all bits from bitset.
5	bitset::fpp() `single bit` Toggles single bit from bitset.
6	bitset::none() Tests whether all bits are unset or not.
7	bitset::operator[] `bool version` Returns the value of bit at position `pos`.
8	bitset::operator[] `reference version` Returns the reference of bit at position `pos`.
9	bitset::reset() `all bits` Reset all bits of bitset to zero.
10	bitset::reset() `single bit` Reset single bit of bitset to zero.
11	bitset::set() `all bits` Set all bits from bitset to one.
12	bitset::set() `single bit` Set single bit from bitset to either `one` or `zero`.
13	bitset::size() Reports the size of the bitset.
14	bitset::test() Tests whether N^th bit is set or not.
15	bitset::to_string() Converts bitset object to string object.
16	bitset::to_ullong() Convert bitset to unsigned long long.
17	bitset::to_ulong() Convert bitset to unsigned long.

Non-member functions

Sr.No.	Method & Description
1	bitset::hash() Returns hash value based on the provided bitset.