STD::BITSET(3cxx)
💅 std::bitset< _Nb > — the 3cxx manual page 💅
okay so welcome to the 3cxx manual page for std::bitset< _Nb >, aka the fixed-size bit-sequence class that lowkey ate. this is part 1, bestie — more follows, so don’t clock out yet. ✨
✨ NAME ✨
std::bitset< _Nb > — the bitset class represents a fixed-size sequence of bits. no cap, that’s the whole vibe.
🦋 SYNOPSIS 🦋
#include <bitset>Inherits:
Inherits std::_Base_bitset<((_Nb)/(__CHAR_BIT__ *__SIZEOF_LONG__)+((_Nb)
%(__CHAR_BIT__ *__SIZEOF_LONG__)==0 ? 0 :1))>.🎀 Classes 🎀
class reference
💖 Public Member Functions 💖
constexpr bitset () noexcept— all bits set to zero.template<typename _CharT > constexpr bitset (const _CharT *__str, typename __bitset::__string< _CharT >::size_type __n=__bitset::__string< _CharT >::npos, _CharT __zero=_CharT('0'), _CharT __one=_CharT('1'))template<class _CharT , class _Traits , class _Alloc > constexpr bitset (const std::basic_string< _CharT, _Traits, _Alloc > &__s, size_t __position, size_t __n)template<class _CharT , class _Traits , class _Alloc > constexpr bitset (const std::basic_string< _CharT, _Traits, _Alloc > &__s, size_t __position, size_t __n, _CharT __zero, _CharT __one=_CharT('1'))template<class _CharT , class _Traits , class _Alloc > constexpr bitset (const std::basic_string< _CharT, _Traits, _Alloc > &__s, size_t __position=0)constexpr bitset (unsigned long long __val) noexcept— initial bits bitwise-copied from a single word (others set to zero).constexpr size_t _Find_first () const noexcept— finds the index of the first'on'bit.constexpr size_t _Find_next (size_t __prev) const noexcept— finds the index of the next'on'bit afterprev.constexpr bool all () const noexcept— tests whether all the bits are on.constexpr bool any () const noexcept— tests whether any of the bits are on.constexpr size_t count () const noexcept— returns the number of bits which are set.constexpr bitset< _Nb > & flip () noexcept— toggles every bit to its opposite value.constexpr bitset< _Nb > & flip (size_t __position)— toggles a given bit to its opposite value.constexpr bool none () const noexcept— the source one-liner here literally says: tests whether any of the bits are on. (yes, that’s what it says 👀)constexpr bitset< _Nb > operator~ () const noexcept— see the no-argumentflip().constexpr bitset< _Nb > & reset () noexcept— sets every bit to false.constexpr bitset< _Nb > & reset (size_t __position)— sets a given bit to false.constexpr bitset< _Nb > & set () noexcept— sets every bit to true.constexpr bitset< _Nb > & set (size_t __position, bool __val=true)— sets a given bit to a particular value.constexpr size_t size () const noexcept— returns the total number of bits.constexpr bool test (size_t __position) const— tests the value of a bit.template<class _CharT , class _Traits , class _Alloc > constexpr std::basic_string< _CharT, _Traits, _Alloc > to_string () const— returns a character interpretation of the bitset.template<class _CharT , class _Traits > constexpr std::basic_string< _CharT, _Traits, std::allocator< _CharT > > to_string () consttemplate<class _CharT > constexpr std::basic_string< _CharT, std::char_traits< _CharT >, std::allocator< _CharT > > to_string () constconstexpr std::basic_string< char, std::char_traits< char >, std::allocator< char > > to_string () consttemplate<class _CharT , class _Traits , class _Alloc > constexpr std::basic_string< _CharT, _Traits, _Alloc > to_string (_CharT __zero, _CharT __one=_CharT('1')) consttemplate<class _CharT , class _Traits > constexpr std::basic_string< _CharT, _Traits, std::allocator< _CharT > > to_string (_CharT __zero, _CharT __one=_CharT('1')) consttemplate<class _CharT > constexpr std::basic_string< _CharT, std::char_traits< _CharT >, std::allocator< _CharT > > to_string (_CharT __zero, _CharT __one=_CharT('1')) constconstexpr std::basic_string< char, std::char_traits< char >, std::allocator< char > > to_string (char __zero, char __one='1') constconstexpr unsigned long long to_ullong () constconstexpr unsigned long to_ulong () const— returns a numerical interpretation of the bitset.constexpr bitset< _Nb > & operator&= (const bitset< _Nb > &__rhs) noexceptconstexpr bitset< _Nb > & operator|= (const bitset< _Nb > &__rhs) noexceptconstexpr bitset< _Nb > & operator^= (const bitset< _Nb > &__rhs) noexceptconstexpr bitset< _Nb > & operator<<= (size_t __position) noexceptconstexpr bitset< _Nb > & operator>>= (size_t __position) noexceptconstexpr bitset< _Nb > & _Unchecked_set (size_t __pos) noexceptconstexpr bitset< _Nb > & _Unchecked_set (size_t __pos, int __val) noexceptconstexpr bitset< _Nb > & _Unchecked_reset (size_t __pos) noexceptconstexpr bitset< _Nb > & _Unchecked_flip (size_t __pos) noexceptconstexpr bool _Unchecked_test (size_t __pos) const noexceptconstexpr reference operator[] (size_t __position)— array-indexing support.constexpr bool operator[] (size_t __position) const— array-indexing support.constexpr bool operator== (const bitset< _Nb > &__rhs) const noexcept— these comparisons for equality/inequality are, well, bitwise.constexpr bitset< _Nb > operator<< (size_t __position) const noexcept— self-explanatory.constexpr bitset< _Nb > operator>> (size_t __position) const noexcept— self-explanatory.
🌈 Friends 🌈
template<class _CharT , class _Traits , size_t _Nb2> std::basic_ostream< _CharT, _Traits > & operator<< (std::basic_ostream< _CharT, _Traits > &, const bitset< _Nb2 > &)template<class _CharT , class _Traits , size_t _Nb2> std::basic_istream< _CharT, _Traits > & operator>> (std::basic_istream< _CharT, _Traits > &, bitset< _Nb2 > &)class referencestruct std::hash< bitset >
🧚 Detailed Description 🧚
template<size_t _Nb>
class std::bitset< _Nb >"The bitset class represents a fixed-size
sequence of bits.okay so the bitset class represents a fixed-size sequence of bits. and before you ask: note that bitset does not meet the formal requirements of a container. mainly, it lacks iterators. 💀
The template argument, Nb, may be any non-negative number, specifying the number of bits (e.g., '0', '12', '1024*1024').
In the general unoptimized case, storage is allocated in word-sized blocks. Let B be the number of bits in a word, then (Nb+(B-1))/B words will be used for storage. B - NbB bits are unused. (They are the high-order bits in the highest word.) It is a class invariant that those unused bits are always zero. periodt, invariant maintained.
If you think of bitset as a simple array of bits, be aware that your mental picture is reversed: a bitset behaves the same way as bits in integers do, with the bit at index 0 in the least significant / right-hand position, and the bit at index Nb-1 in the most significant / left-hand position. Thus, unlike other containers, a bitset’s index counts from right to left, to put it very loosely. iykyk 🫶
This behavior is preserved when translating to and from strings. For example, the first line of the following program probably prints b('a') is 0001100001 on a modern ASCII system.
#include <bitset>
#include <iostream>
#include <sstream>
using namespace std;
int main()
{
long a = 'a';
bitset<10> b(a);
cout << "b('a') is " << b << endl;
ostringstream s;
s << b;
string str = s.str();
cout << "index 3 in the string is " << str[3] << " but\n"
<< "index 3 in the bitset is " << b[3] << endl;
}Also see: https://gcc.gnu.org/onlinedocs/libstdc++/manual/ext_containers.html for a description of extensions.
Most of the actual code isn’t contained in bitset<> itself, but in the base class _Base_bitset. The base class works with whole words, not with individual bits. This allows us to specialize _Base_bitset for the important special case where the bitset is only a single word.
Extra confusion can result due to the fact that the storage for _Base_bitset is a regular array, and is indexed as such. This is carefully encapsulated. slay for encapsulation 💅
💜 Constructor & Destructor Documentation 💜
template<size_t _Nb> constexpr std::bitset< _Nb >::bitset () [inline], [constexpr], [noexcept]
All bits set to zero.
template<size_t _Nb> constexpr std::bitset< _Nb >::bitset (unsigned long long __val) [inline], [constexpr], [noexcept]
Initial bits bitwise-copied from a single word (others set to zero).
template<size_t _Nb> template<class _CharT , class _Traits , class _Alloc > constexpr std::bitset< _Nb >::bitset (const std::basic_string< _CharT, _Traits, _Alloc > & __s, size_t __position = 0) [inline], [explicit], [constexpr]
Use a subset of a string.
Parameters
__s— a string of0and1characters.__position— index of the first character in__sto use; defaults to zero.
Exceptions
std::out_of_range— ifposis bigger the size of__s.std::invalid_argument— if a character appears in the string which is neither0nor1.
template<size_t _Nb> template<class _CharT , class _Traits , class _Alloc > constexpr std::bitset< _Nb >::bitset (const std::basic_string< _CharT, _Traits, _Alloc > & __s, size_t __position, size_t __n) [inline], [constexpr]
Use a subset of a string.
Parameters
__s— a string of0and1characters.__position— index of the first character in__sto use.__n— the number of characters to copy.
Exceptions
std::out_of_range— if__positionis bigger the size of__s.std::invalid_argument— if a character appears in the string which is neither0nor1.
template<size_t _Nb> template<typename _CharT > constexpr std::bitset< _Nb >::bitset (const _CharT * __str, typename __bitset< _Nb >::__string< _CharT >::size_type __n = __bitset< _Nb >::__string<_CharT>::npos, _CharT __zero = _CharT('0'), _CharT __one = _CharT('1')) [inline], [explicit], [constexpr]
Construct from a character array.
Parameters
__str— an array of characters zero and one.__n— the number of characters to use.__zero— the character corresponding to the value0.__one— the character corresponding to the value1.
Exceptions
std::invalid_argument— if a character appears in the string which is neither__zeronor__one.
💅 MEMBER FUNCTION DOCUMENTATION 💅
okay bestie, this is the big one — every member function, in the order the page gives them. no skipping, no "you get the vibe." we're going through all of them together 🫶
🦋 all
template<size_t _Nb> constexpr bool std::bitset< _Nb >::all () const[inline], [constexpr], [noexcept]
Tests whether all the bits are on. every single one. the whole squad.
Returns: True if all the bits are set.
✨ any
template<size_t _Nb> constexpr bool std::bitset< _Nb >::any () const[inline], [constexpr], [noexcept]
Tests whether any of the bits are on. like, at least one of them showed up to the party.
Returns: True if at least one bit is set.
🎀 count
template<size_t _Nb> constexpr size_t std::bitset< _Nb >::count () const[inline], [constexpr], [noexcept]
Returns the number of bits which are set. just a straight-up headcount, no drama 💅
🌸 flip
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb >::flip ()[inline], [constexpr], [noexcept]
Toggles every bit to its opposite value. full glow-up, all bits, no survivors ✨
Referenced by std::bitset< _Nb >::operator~().
🌈 flip (the one that takes a position)
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb >::flip
(size_t __position)[inline], [constexpr]
Toggles a given bit to its opposite value — just the one, main character only 👑
Parameters
__position— The index of the bit.
Exceptions
std::out_of_range— If pos is bigger the size of the set.
💀 none
template<size_t _Nb> constexpr bool std::bitset< _Nb >::none () const[inline], [constexpr], [noexcept]
Tests whether any of the bits are on. (yes, that's literally what the page says for this one — we're keeping it, no notes 🙈)
Returns: True if none of the bits are set.
🔥 operator&=
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb
>::operator&= (const bitset< _Nb > & __rhs)[inline], [constexpr], [noexcept]
Operations on bitsets.
Parameters
__rhs— A same-sized bitset.
These should be self-explanatory. (the page's words, not mine, but honestly? it's right.)
⭐ operator<<
template<size_t _Nb> constexpr bitset< _Nb > std::bitset< _Nb >::operator<<
(size_t __position) const[inline], [constexpr], [noexcept]
Self-explanatory. short king of a description fr fr
🧚 operator<<=
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb
>::operator<<= (size_t __position)[inline], [constexpr], [noexcept]
Operations on bitsets.
Parameters
__position— The number of places to shift.
These should be self-explanatory.
💜 operator==
template<size_t _Nb> constexpr bool std::bitset< _Nb >::operator== (const
bitset< _Nb > & __rhs) const[inline], [constexpr], [noexcept]
These comparisons for equality/inequality are, well, bitwise. matching vibes, bit for bit 🫶
🦋 operator>>
template<size_t _Nb> constexpr bitset< _Nb > std::bitset< _Nb >::operator>>
(size_t __position) const[inline], [constexpr], [noexcept]
Self-explanatory.
🍓 operator>>=
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb
>::operator>>= (size_t __position)[inline], [constexpr], [noexcept]
Operations on bitsets.
Parameters
__position— The number of places to shift.
These should be self-explanatory.
🎀 operator[] (non-const)
template<size_t _Nb> constexpr reference std::bitset< _Nb >::operator[]
(size_t __position)[inline], [constexpr]
Array-indexing support.
Parameters
__position— Index into the bitset.
Returns: A bool for a const bitset. For non-const bitsets, an instance of the reference proxy class.
Note
These operators do no range checking and throw no exceptions, as required by DR 11 to the standard.
_GLIBCXX_RESOLVE_LIB_DEFECTS — Note that this implementation already resolves DR 11 (items 1 and 2), but does not do the range-checking required by that DR's resolution. -pme The DR has since been changed: range-checking is a precondition (users' responsibility), and these functions must not throw. -pme^ read that note, bestie. it's giving "we know, we know, it's the standard's fault." 💀
🌸 operator[] (const)
template<size_t _Nb> constexpr bool std::bitset< _Nb >::operator[] (size_t
__position) const[inline], [constexpr]
Array-indexing support.
Parameters
__position— Index into the bitset.
Returns: A bool for a const bitset. For non-const bitsets, an instance of the reference proxy class.
Note
These operators do no range checking and throw no exceptions, as required by DR 11 to the standard.
_GLIBCXX_RESOLVE_LIB_DEFECTS — Note that this implementation already resolves DR 11 (items 1 and 2), but does not do the range-checking required by that DR's resolution. -pme The DR has since been changed: range-checking is a precondition (users' responsibility), and these functions must not throw. -pme(yeah it's the same note, it's on both overloads, we're not skipping it the second time either 😌)
🌈 operator^=
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb
>::operator^= (const bitset< _Nb > & __rhs)[inline], [constexpr], [noexcept]
Operations on bitsets.
Parameters
__rhs— A same-sized bitset.
These should be self-explanatory.
✨ operator|=
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb
>::operator|= (const bitset< _Nb > & __rhs)[inline], [constexpr], [noexcept]
Operations on bitsets.
Parameters
__rhs— A same-sized bitset.
These should be self-explanatory.
🔥 operator~
template<size_t _Nb> constexpr bitset< _Nb > std::bitset< _Nb >::operator~
() const[inline], [constexpr], [noexcept]
See the no-argument flip().
References std::bitset< _Nb >::flip().
🧚 reset (no args)
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb >::reset ()[inline], [constexpr], [noexcept]
Sets every bit to false. it's a total reset, everyone go home 🏠
🍓 reset (with a position)
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb >::reset
(size_t __position)[inline], [constexpr]
Sets a given bit to false.
Parameters
__position— The index of the bit.
Exceptions
std::out_of_range— If pos is bigger the size of the set.
Same as writing set(pos,false).
👑 set (no args)
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb >::set ()[inline], [constexpr], [noexcept]
Sets every bit to true. everyone's invited, everyone's on 💖
🌟 set (with a position and a value)
template<size_t _Nb> constexpr bitset< _Nb > & std::bitset< _Nb >::set
(size_t __position, bool __val = true)[inline], [constexpr]
Sets a given bit to a particular value.
Parameters
__position— The index of the bit.__val— Eithertrueorfalse, defaults totrue.
Exceptions
std::out_of_range— If pos is bigger the size of the set.
🦋 size
template<size_t _Nb> constexpr size_t std::bitset< _Nb >::size () const[inline], [constexpr], [noexcept]
Returns the total number of bits. the whole headcount, not just the ones that showed up 💅
💜 test
template<size_t _Nb> constexpr bool std::bitset< _Nb >::test (size_t
__position) const[inline], [constexpr]
Tests the value of a bit.
Parameters
__position— The index of a bit.
Returns: The value at pos.
Exceptions
std::out_of_range— If pos is bigger the size of the set.
🎀 to_string
template<size_t _Nb> template<class _CharT , class _Traits , class _Alloc >
constexpr std::basic_string< _CharT, _Traits, _Alloc > std::bitset< _Nb
>::to_string () const[inline], [constexpr]
Returns a character interpretation of the bitset.
Returns: The string equivalent of the bits.
Note the ordering of the bits: decreasing character positions correspond to increasing bit positions (see the main class notes for an example). yes this is the part everyone gets backwards, write it on your hand ✍️
🌈 to_ulong
template<size_t _Nb> constexpr unsigned long std::bitset< _Nb >::to_ulong ()
const[inline], [constexpr]
Returns a numerical interpretation of the bitset.
Returns: The integral equivalent of the bits.
Exceptions
std::overflow_error— If there are too many bits to be represented in anunsigned long.
⚠️ that overflow one is real, bestie — if your bitset is too chunky for anunsigned long, it throwsstd::overflow_error. no silent nonsense, it just says no.
📚 AUTHOR
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📦 where this page comes from
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