std::bitset< _Nb > Class Template Reference
Utilities
Inheritance diagram for std::bitset< _Nb >:
[legend]

## Classes

class | reference

## Public Member Functions

constexpr | bitset () noexcept
constexpr | bitset (unsigned long long __val) noexcept
template<class _CharT , class _Traits , class _Alloc >
| bitset (const std::basic_string< _CharT, _Traits, _Alloc > &__s, size_t __position=0)
template<class _CharT , class _Traits , class _Alloc >
| bitset (const std::basic_string< _CharT, _Traits, _Alloc > &__s, size_t __position, size_t __n)
template<class _CharT , class _Traits , class _Alloc >
| bitset (const std::basic_string< _CharT, _Traits, _Alloc > &__s, size_t __position, size_t __n, _CharT __zero, _CharT __one=_CharT('1'))
template<typename _CharT >
| bitset (const _CharT *__str, typename std::basic_string< _CharT >::size_type __n=std::basic_string< _CharT >::npos, _CharT __zero=_CharT('0'), _CharT __one=_CharT('1'))
size_t | _Find_first () const noexcept
size_t | _Find_next (size_t __prev) const noexcept
template<class _CharT , class _Traits >
void | _M_copy_from_ptr (const _CharT *, size_t, size_t, size_t, _CharT, _CharT)
template<class _CharT , class _Traits , class _Alloc >
void | _M_copy_from_string (const std::basic_string< _CharT, _Traits, _Alloc > &__s, size_t __pos, size_t __n, _CharT __zero, _CharT __one)
template<class _CharT , class _Traits , class _Alloc >
void | _M_copy_from_string (const std::basic_string< _CharT, _Traits, _Alloc > &__s, size_t __pos, size_t __n)
template<class _CharT , class _Traits , class _Alloc >
void | _M_copy_to_string (std::basic_string< _CharT, _Traits, _Alloc > &, _CharT, _CharT) const
template<class _CharT , class _Traits , class _Alloc >
void | _M_copy_to_string (std::basic_string< _CharT, _Traits, _Alloc > &__s) const
bool | all () const noexcept
bool | any () const noexcept
size_t | count () const noexcept
bitset< _Nb > & | flip () noexcept
bitset< _Nb > & | flip (size_t __position)
bool | none () const noexcept
bitset< _Nb > | operator~ () const noexcept
bitset< _Nb > & | reset () noexcept
bitset< _Nb > & | reset (size_t __position)
bitset< _Nb > & | set () noexcept
bitset< _Nb > & | set (size_t __position, bool __val=true)
constexpr size_t | size () const noexcept
bool | test (size_t __position) const
template<class _CharT , class _Traits , class _Alloc >
std::basic_string< _CharT, _Traits, _Alloc > | to_string () const
template<class _CharT , class _Traits , class _Alloc >
std::basic_string< _CharT, _Traits, _Alloc > | to_string (_CharT __zero, _CharT __one=_CharT('1')) const
template<class _CharT , class _Traits >
std::basic_string< _CharT, _Traits, std::allocator< _CharT > > | to_string () const
template<class _CharT , class _Traits >
std::basic_string< _CharT, _Traits, std::allocator< _CharT > > | to_string (_CharT __zero, _CharT __one=_CharT('1')) const
template<class _CharT >
std::basic_string< _CharT, std::char_traits< _CharT >, std::allocator< _CharT > > | to_string () const
template<class _CharT >
std::basic_string< _CharT, std::char_traits< _CharT >, std::allocator< _CharT > > | to_string (_CharT __zero, _CharT __one=_CharT('1')) const
std::basic_string< char, std::char_traits< char >, std::allocator< char > > | to_string () const
std::basic_string< char, std::char_traits< char >, std::allocator< char > > | to_string (char __zero, char __one='1') const
unsigned long long | to_ullong () const
unsigned long | to_ulong () const
bitset< _Nb > & | operator &= (const bitset< _Nb > &__rhs) noexcept
bitset< _Nb > & | operator|= (const bitset< _Nb > &__rhs) noexcept
bitset< _Nb > & | operator^= (const bitset< _Nb > &__rhs) noexcept
bitset< _Nb > & | operator<<= (size_t __position) noexcept
bitset< _Nb > & | operator>>= (size_t __position) noexcept
bitset< _Nb > & | _Unchecked_set (size_t __pos) noexcept
bitset< _Nb > & | _Unchecked_set (size_t __pos, int __val) noexcept
bitset< _Nb > & | _Unchecked_reset (size_t __pos) noexcept
bitset< _Nb > & | _Unchecked_flip (size_t __pos) noexcept
constexpr bool | _Unchecked_test (size_t __pos) const noexcept
reference | operator[] (size_t __position)
constexpr bool | operator[] (size_t __position) const
bool | operator== (const bitset< _Nb > &__rhs) const noexcept
bool | operator!= (const bitset< _Nb > &__rhs) const noexcept
bitset< _Nb > | operator<< (size_t __position) const noexcept
bitset< _Nb > | operator>> (size_t __position) const noexcept

## Private Member Functions

bool | _M_are_all () const noexcept
void | _M_do_and (const _Base_bitset< _Nw > &__x) noexcept
size_t | _M_do_count () const noexcept
size_t | _M_do_find_first (size_t) const noexcept
size_t | _M_do_find_next (size_t, size_t) const noexcept
void | _M_do_flip () noexcept
void | _M_do_left_shift (size_t __shift) noexcept
void | _M_do_or (const _Base_bitset< _Nw > &__x) noexcept
void | _M_do_reset () noexcept
void | _M_do_right_shift (size_t __shift) noexcept
void | _M_do_set () noexcept
unsigned long long | _M_do_to_ullong () const
unsigned long | _M_do_to_ulong () const
void | _M_do_xor (const _Base_bitset< _Nw > &__x) noexcept
const _WordT * | _M_getdata () const noexcept
_WordT & | _M_getword (size_t __pos) noexcept
constexpr _WordT | _M_getword (size_t __pos) const noexcept
_WordT & | _M_hiword () noexcept
constexpr _WordT | _M_hiword () const noexcept
bool | _M_is_any () const noexcept
bool | _M_is_equal (const _Base_bitset< _Nw > &__x) const noexcept

## Static Private Member Functions

static constexpr _WordT | _S_maskbit (size_t __pos) noexcept
static constexpr size_t | _S_whichbit (size_t __pos) noexcept
static constexpr size_t | _S_whichbyte (size_t __pos) noexcept
static constexpr size_t | _S_whichword (size_t __pos) noexcept

## Private Attributes

_WordT | _M_w [_Nw]

## Friends

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.

Definition at line 751 of file bitset.

## Constructor & Destructor Documentation

## bitset() [1/5]

template<size_t _Nb>

constexpr std::bitset< _Nb >::bitset | ( |  | ) |

inline noexcept

All bits set to zero.

Definition at line 865 of file bitset.

## bitset() [2/5]

template<size_t _Nb>

constexpr std::bitset< _Nb >::bitset | ( | unsigned long long | __val | ) |

inline noexcept

Initial bits bitwise-copied from a single word (others set to zero).

Definition at line 870 of file bitset.

## bitset() [3/5]

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

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 pos is bigger the size of __s.
  std::invalid_argument | If a character appears in the string which is neither 0 nor 1.

Definition at line 889 of file bitset.

## bitset() [4/5]

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

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 is bigger the size of __s.
  std::invalid_argument | If a character appears in the string which is neither 0 nor 1.

Definition at line 910 of file bitset.

## bitset() [5/5]

template<size_t _Nb>
template<typename _CharT >

std::bitset< _Nb >::bitset | ( | const _CharT * | __str,
|  | typename std::basic_string< _CharT >::size_type | __n = `std::basic_string<_CharT>::npos`,
|  | _CharT | __zero = `_CharT('0')`,
|  | _CharT | __one = `_CharT('1')`
| ) |  |

inline explicit

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.

Definition at line 942 of file bitset.

## Member Function Documentation

## all()

template<size_t _Nb>

bool std::bitset< _Nb >::all | ( |  | ) | const

inline noexcept

Tests whether all the bits are on.

Returns
  True if all the bits are set.

Definition at line 1330 of file bitset.

## any()

template<size_t _Nb>

bool std::bitset< _Nb >::any | ( |  | ) | const

inline noexcept

Tests whether any of the bits are on.

Returns
  True if at least one bit is set.

Definition at line 1338 of file bitset.

## count()

template<size_t _Nb>

size_t std::bitset< _Nb >::count | ( |  | ) | const

inline noexcept

Returns the number of bits which are set.

Definition at line 1291 of file bitset.

## flip() [1/2]

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::flip | ( |  | ) |

inline noexcept

Toggles every bit to its opposite value.

Definition at line 1119 of file bitset.

Referenced by std::bitset< _Nb >::operator~().

## flip() [2/2]

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::flip | ( | size_t | __position | ) |

inline

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.

Definition at line 1132 of file bitset.

## none()

template<size_t _Nb>

bool std::bitset< _Nb >::none | ( |  | ) | const

inline noexcept

Tests whether any of the bits are on.

Returns
  True if none of the bits are set.

Definition at line 1346 of file bitset.

## operator &=()

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::operator&= | ( | const bitset< _Nb > & | __rhs | ) |

inline noexcept

Operations on bitsets.

Parameters

  __rhs | A same-sized bitset.

These should be self-explanatory.

Definition at line 968 of file bitset.

## operator!=()

template<size_t _Nb>

bool std::bitset< _Nb >::operator!= | ( | const bitset< _Nb > & | __rhs | ) | const

inline noexcept

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

Definition at line 1306 of file bitset.

## operator<<()

template<size_t _Nb>

bitset<_Nb> std::bitset< _Nb >::operator<< | ( | size_t | __position | ) | const

inline noexcept

Self-explanatory.

Definition at line 1352 of file bitset.

## operator<<=()

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::operator<<= | ( | size_t | __position | ) |

inline noexcept

Operations on bitsets.

Parameters

  __position | The number of places to shift.

These should be self-explanatory.

Definition at line 997 of file bitset.

## operator==()

template<size_t _Nb>

bool std::bitset< _Nb >::operator== | ( | const bitset< _Nb > & | __rhs | ) | const

inline noexcept

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

Definition at line 1302 of file bitset.

## operator>>()

template<size_t _Nb>

bitset<_Nb> std::bitset< _Nb >::operator>> | ( | size_t | __position | ) | const

inline noexcept

Self-explanatory.

Definition at line 1356 of file bitset.

## operator>>=()

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::operator>>= | ( | size_t | __position | ) |

inline noexcept

Operations on bitsets.

Parameters

  __position | The number of places to shift.

These should be self-explanatory.

Definition at line 1010 of file bitset.

## operator[]() [1/2]

template<size_t _Nb>

reference std::bitset< _Nb >::operator[] | ( | size_t | __position | ) |

inline

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

Definition at line 1159 of file bitset.

## operator[]() [2/2]

template<size_t _Nb>

constexpr bool std::bitset< _Nb >::operator[] | ( | size_t | __position | ) | const

inline

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

Definition at line 1163 of file bitset.

## operator^=()

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::operator^= | ( | const bitset< _Nb > & | __rhs | ) |

inline noexcept

Operations on bitsets.

Parameters

  __rhs | A same-sized bitset.

These should be self-explanatory.

Definition at line 982 of file bitset.

## operator|=()

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::operator|= | ( | const bitset< _Nb > & | __rhs | ) |

inline noexcept

Operations on bitsets.

Parameters

  __rhs | A same-sized bitset.

These should be self-explanatory.

Definition at line 975 of file bitset.

## operator~()

template<size_t _Nb>

bitset<_Nb> std::bitset< _Nb >::operator~ | ( |  | ) | const

inline noexcept

See the no-argument flip().

Definition at line 1140 of file bitset.

References std::bitset< _Nb >::flip().

## reset() [1/2]

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::reset | ( |  | ) |

inline noexcept

Sets every bit to false.

Definition at line 1095 of file bitset.

## reset() [2/2]

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::reset | ( | size_t | __position | ) |

inline

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)`.

Definition at line 1109 of file bitset.

## set() [1/2]

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::set | ( |  | ) |

inline noexcept

Sets every bit to true.

Definition at line 1071 of file bitset.

## set() [2/2]

template<size_t _Nb>

bitset<_Nb>& std::bitset< _Nb >::set | ( | size_t | __position,
|  | bool | __val = `true`
| ) |  |

inline

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.

Definition at line 1085 of file bitset.

## size()

template<size_t _Nb>

constexpr size_t std::bitset< _Nb >::size | ( |  | ) | const

inline noexcept

Returns the total number of bits.

Definition at line 1296 of file bitset.

## test()

template<size_t _Nb>

bool std::bitset< _Nb >::test | ( | size_t | __position | ) | const

inline

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.

Definition at line 1317 of file bitset.

## to_string()

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

std::basic_string<_CharT, _Traits, _Alloc> std::bitset< _Nb >::to_string | ( |  | ) | const

inline

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).

Definition at line 1193 of file bitset.

References std::basic_string< _CharT, _Traits, _Alloc >::data(), and std::basic_string< _CharT, _Traits, _Alloc >::size().

## to_ulong()

template<size_t _Nb>

unsigned long std::bitset< _Nb >::to_ulong | ( |  | ) | const

inline

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`.

Definition at line 1174 of file bitset.

The documentation for this class was generated from the following file:

- bitset