STD::BITSET(3)

📦
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✨ std::bitset< _Nb > — from the Library Functions Manual, section 3 ✨

okay bestie, buckle up, we're doing std::bitset today and honestly? she's a whole icon. 💅

🌸 NAME 🌸

std::bitset< _Nb > — The bitset class represents a fixed-size sequence of bits.

🎀 SYNOPSIS 🎀

#include <bitset>

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, typename = _Require<is_trivially_copyable<_CharT>, is_standard_layout<_CharT>, is_trivially_default_constructible<_CharT>, __not_<is_array<_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 after prev.
  • 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 — Tests whether any of the bits are on. (yes that's literally what the page says, bestie, I'm just the messenger 💀)
  • constexpr bitset< _Nb > operator~ () const noexcept — See the no-argument flip().
  • 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.
  • constexpr std::basic_string< char, std::char_traits< char >, std::allocator< char > > to_string () const
  • template<class _CharT> constexpr std::basic_string< _CharT, std::char_traits< _CharT >, std::allocator< _CharT > > to_string () const
  • template<class _CharT, class _Traits> constexpr std::basic_string< _CharT, _Traits, std::allocator< _CharT > > to_string () const
  • 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> constexpr std::basic_string< _CharT, std::char_traits< _CharT >, std::allocator< _CharT > > to_string (_CharT __zero, _CharT __one=_CharT('1')) const
  • template<class _CharT, class _Traits> constexpr std::basic_string< _CharT, _Traits, std::allocator< _CharT > > to_string (_CharT __zero, _CharT __one=_CharT('1')) const
  • template<class _CharT, class _Traits, class _Alloc> constexpr std::basic_string< _CharT, _Traits, _Alloc > to_string (_CharT __zero, _CharT __one=_CharT('1')) const
  • constexpr std::basic_string< char, std::char_traits< char >, std::allocator< char > > to_string (char __zero, char __one='1') const
  • constexpr unsigned long long to_ullong () const
  • constexpr unsigned long to_ulong () const — Returns a numerical interpretation of the bitset.

and then, nested in there, a whole lil squad of operator besties 👇

  • constexpr bitset< _Nb > & operator&= (const bitset< _Nb > &__rhs) noexcept
  • constexpr bitset< _Nb > & operator|= (const bitset< _Nb > &__rhs) noexcept
  • constexpr bitset< _Nb > & operator^= (const bitset< _Nb > &__rhs) noexcept
  • constexpr bitset< _Nb > & operator<<= (size_t __position) noexcept
  • constexpr bitset< _Nb > & operator>>= (size_t __position) noexcept
  • constexpr bitset< _Nb > & _Unchecked_set (size_t __pos) noexcept
  • constexpr bitset< _Nb > & _Unchecked_set (size_t __pos, int __val) noexcept
  • constexpr bitset< _Nb > & _Unchecked_reset (size_t __pos) noexcept
  • constexpr bitset< _Nb > & _Unchecked_flip (size_t __pos) noexcept
  • constexpr bool _Unchecked_test (size_t __pos) const noexcept
  • constexpr 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 reference
  • struct std::hash< bitset >

👑 Detailed Description 👑

template<size_t _Nb>
    class std::bitset< _Nb >

"The bitset class represents a fixed-size sequence of bits.

(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.

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. 💫

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.

🌈 Constructor & Destructor Documentation 🌈

template<size_t _Nb> std::bitset< _Nb >::bitset () [inline], [constexpr], [noexcept]

All bits set to zero.

Referenced by operator&=(), operator<<(), operator<<=(), operator==(), operator>>(), operator^=(), operator|=(), and operator~().

template<size_t _Nb> 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> 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 of 0 and 1 characters.
  • __position — Index of the first character in __s to use; defaults to zero.

Exceptions

  • std::out_of_range — If __position > __s.size().
  • std::invalid_argument — If a character appears in the string which is neither 0 nor 1.

References std::basic_string< _CharT, _Traits, _Alloc >::npos.

template<size_t _Nb> template<class _CharT, class _Traits, class _Alloc> 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 of 0 and 1 characters.
  • __position — Index of the first character in __s to use.
  • __n — The number of characters to copy.

Exceptions

  • std::out_of_range — If __position > __s.size().
  • std::invalid_argument — If a character appears in the string which is neither 0 nor 1.

template<size_t _Nb> template<typename _CharT, typename = _Require<is_trivially_copyable<_CharT>, is_standard_layout<_CharT>, is_trivially_default_constructible<_CharT>, __not_<is_array<_CharT>>>> 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 value 0.
  • __one — The character corresponding to the value 1.

Exceptions

  • std::invalid_argument — If a character appears in the string which is neither __zero nor __one.

References std::basic_string< _CharT >::npos.

...and that's part 1 bestie, there's MORE coming so don't you dare close the tab 🫶✨

✨ Member Function Documentation ✨

okay bestie, this is the part where we go through every single member function like we're doing a makeup review. no skips. 💅

template<size_t _Nb> bool std::bitset< _Nb >::all () const [inline], [constexpr], [noexcept]

This one tests whether all the bits are on. literally the "is everyone here?" roll call.

Returns: true if all the bits are set. 💖

template<size_t _Nb> bool std::bitset< _Nb >::any () const [inline], [constexpr], [noexcept]

Tests whether any of the bits are on.

Returns: true if at least one bit is set. periodt. ✨

template<size_t _Nb> size_t std::bitset< _Nb >::count () const [inline], [constexpr], [noexcept]

Returns the number of bits which are set. it's giving census energy. 🧚

template<size_t _Nb> bitset< _Nb > & std::bitset< _Nb >::flip () [inline], [constexpr], [noexcept]

Toggles every bit to its opposite value. the whole set is flipping, no cap. 🔄

template<size_t _Nb> bitset< _Nb > & std::bitset< _Nb >::flip (size_t __position) [inline], [constexpr]

Toggles a given bit to its opposite value.

  • Parameters: __position — The index of the bit.
  • Exceptions: std::out_of_range — If pos is bigger the size of the set.
References: _Unchecked_flip().

template<size_t _Nb> bool std::bitset< _Nb >::none () const [inline], [constexpr], [noexcept]

Tests whether any of the bits are on. (yes, the description is worded like that, we're keeping it exactly.)

Returns: true if none of the bits are set. 💀

template<size_t _Nb> 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. slay.

References: bitset().

template<size_t _Nb> bitset< _Nb > std::bitset< _Nb >::operator<< (size_t __position) const [inline], [constexpr], [noexcept]

Self-explanatory. 💅

References: bitset().

template<size_t _Nb> 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.

References: bitset(), and operator<<=(). Referenced by: operator<<=().

template<size_t _Nb> bool std::bitset< _Nb >::operator== (const bitset< _Nb > & __rhs) const [inline], [constexpr], [noexcept]

These comparisons for equality/inequality are, well, bitwise. iconic.

References: bitset().

template<size_t _Nb> bitset< _Nb > std::bitset< _Nb >::operator>> (size_t __position) const [inline], [constexpr], [noexcept]

Self-explanatory.

References: bitset().

template<size_t _Nb> 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.

template<size_t _Nb> 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

template<size_t _Nb> 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
References: _Unchecked_test().

template<size_t _Nb> 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.

References: bitset().

template<size_t _Nb> 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.

References: bitset().

template<size_t _Nb> bitset< _Nb > std::bitset< _Nb >::operator~ () const [inline], [constexpr], [noexcept]

See the no-argument flip(). 💖

References: bitset().

template<size_t _Nb> bitset< _Nb > & std::bitset< _Nb >::reset () [inline], [constexpr], [noexcept]

Sets every bit to false. the ultimate clear-my-inbox moment. 🧹

template<size_t _Nb> 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).

References: _Unchecked_reset().

template<size_t _Nb> bitset< _Nb > & std::bitset< _Nb >::set () [inline], [constexpr], [noexcept]

Sets every bit to true. all the lights on. 🔥

template<size_t _Nb> 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 — Either true or false, defaults to true.
  • Exceptions: std::out_of_range — If pos is bigger the size of the set.
References: _Unchecked_set().

template<size_t _Nb> size_t std::bitset< _Nb >::size () const [inline], [constexpr], [noexcept]

Returns the total number of bits. the headcount. 👑

template<size_t _Nb> 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.
References: _Unchecked_test().

template<size_t _Nb> template<class _CharT, class _Traits, class _Alloc> 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).

template<size_t _Nb> 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 an unsigned long.

📝 Author 📝

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