std::bitset(3)

NAME
std::bitset - The bitset class represents a fixed-size sequence of bits.

SYNOPSIS

Inherits _Base_bitset<((_Nb)< 1?0:((_Nb)+(__CHAR_BIT__ *sizeof(unsigned long))-1)/(__CHAR_BIT__ *sizeof(unsigned long)))>.

  Classes
class reference

  Public Member Functions
size_t _Find_first () const
size_t _Find_next (size_t __prev) const
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)
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_to_string (std::basic_string< _CharT, _Traits, _Alloc > &__s) const
template<class _CharT , class _Traits , class _Alloc > void _M_copy_to_string (std::basic_string< _CharT, _Traits, _Alloc > &, _CharT, _CharT) const
bool all () const
bool any () const
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<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=0)
bitset (unsigned long __val)
bitset ()
size_t count () const
bitset< _Nb > & flip (size_t __position)
bitset< _Nb > & flip ()
bool none () const
bitset< _Nb > operator~ () const
bitset< _Nb > & reset (size_t __position)
bitset< _Nb > & reset ()
bitset< _Nb > & set (size_t __position, bool __val=true)
bitset< _Nb > & set ()
size_t size () const
bool test (size_t __position) const
std::basic_string< char, std::char_traits< char >, std::allocator< char > > to_string (char __zero, char __one= '1') const
std::basic_string< char, std::char_traits< char >, std::allocator< char > > 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
template<class _CharT > std::basic_string< _CharT, std::char_traits< _CharT >, 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 , class _Traits > std::basic_string< _CharT, _Traits, std::allocator< _CharT > > 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 , class _Alloc > std::basic_string< _CharT, _Traits, _Alloc > to_string () const
unsigned long to_ulong () const

bitset< _Nb > & _Unchecked_flip (size_t __pos)
bitset< _Nb > & _Unchecked_reset (size_t __pos)
bitset< _Nb > & _Unchecked_set (size_t __pos, int __val)
bitset< _Nb > & _Unchecked_set (size_t __pos)
bool _Unchecked_test (size_t __pos) const

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

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

bitset< _Nb > operator<< (size_t __position) const
bitset< _Nb > operator>> (size_t __position) const

bitset< _Nb > & operator<<= (size_t __position)
bitset< _Nb > & operator>>= (size_t __position)

bool operator[] (size_t __position) const
reference operator[] (size_t __position)

  Private Types
typedef unsigned long _WordT

  Private Member Functions
size_t _M_are_all_aux () const
void _M_do_and (const _Base_bitset< _Nw > &__x)
size_t _M_do_count () const
size_t _M_do_find_first (size_t __not_found) const
size_t _M_do_find_next (size_t __prev, size_t __not_found) const
void _M_do_flip ()
void _M_do_left_shift (size_t __shift)
void _M_do_or (const _Base_bitset< _Nw > &__x)
void _M_do_reset ()
void _M_do_right_shift (size_t __shift)
void _M_do_set ()
unsigned long _M_do_to_ulong () const
void _M_do_xor (const _Base_bitset< _Nw > &__x)
_WordT _M_getword (size_t __pos) const
_WordT & _M_getword (size_t __pos)
_WordT _M_hiword () const
_WordT & _M_hiword ()
bool _M_is_any () const
bool _M_is_equal (const _Base_bitset< _Nw > &__x) const

  Static Private Member Functions
static _WordT _S_maskbit (size_t __pos)
static size_t _S_whichbit (size_t __pos)
static size_t _S_whichbyte (size_t __pos)
static size_t _S_whichword (size_t __pos)

  Private Attributes
_WordT _M_w [_Nw]

  Friends
class reference

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
              << 'index 3 in the bitset is ' << b[3] << endl;
     }

Also see: http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt12ch33s02.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 651 of file bitset.

Constructor & Destructor Documentation

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

All bits set to zero.

Definition at line 741 of file bitset.

  template<size_t _Nb> std::bitset< _Nb >::bitset (unsigned long __val) [inline]

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

Definition at line 745 of file bitset.

  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 760 of file bitset.

  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 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 782 of file bitset.

Member Function Documentation

  template<size_t _Nb> bitset<_Nb>& std::bitset< _Nb >::_Unchecked_flip (size_t __pos) [inline]

These versions of single-bit set, reset, flip, and test are extensions from the SGI version. They do no range checking.

Definition at line 901 of file bitset.

  template<size_t _Nb> bitset<_Nb>& std::bitset< _Nb >::_Unchecked_reset (size_t __pos) [inline]

These versions of single-bit set, reset, flip, and test are extensions from the SGI version. They do no range checking.

Definition at line 894 of file bitset.

  template<size_t _Nb> bitset<_Nb>& std::bitset< _Nb >::_Unchecked_set (size_t __pos, int __val) [inline]

These versions of single-bit set, reset, flip, and test are extensions from the SGI version. They do no range checking.

Definition at line 884 of file bitset.

  template<size_t _Nb> bool std::bitset< _Nb >::_Unchecked_test (size_t __pos) const [inline]

These versions of single-bit set, reset, flip, and test are extensions from the SGI version. They do no range checking.

Definition at line 908 of file bitset.

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

Tests whether all the bits are on.

Returns:
    True if all the bits are set.

Definition at line 1175 of file bitset.

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

Tests whether any of the bits are on.

Returns:
    True if at least one bit is set.

Definition at line 1183 of file bitset.

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

Returns the number of bits which are set.

Definition at line 1135 of file bitset.

  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 981 of file bitset.

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

Toggles every bit to its opposite value.

Definition at line 968 of file bitset.

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

Tests whether any of the bits are on.

Returns:
    True if none of the bits are set.

Definition at line 1191 of file bitset.

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

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

Definition at line 1150 of file bitset.

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

Operations on bitsets.

Parameters:
    rhs A same-sized bitset.

These should be self-explanatory.

Definition at line 815 of file bitset.

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

Self-explanatory.

Definition at line 1197 of file bitset.

  template<size_t _Nb> bitset<_Nb>& std::bitset< _Nb >::operator<<= (size_t __position) [inline]

Operations on bitsets.

Parameters:
    position The number of places to shift.

These should be self-explanatory.

Definition at line 844 of file bitset.

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

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

Definition at line 1146 of file bitset.

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

Self-explanatory.

Definition at line 1201 of file bitset.

  template<size_t _Nb> bitset<_Nb>& std::bitset< _Nb >::operator>>= (size_t __position) [inline]

Operations on bitsets.

Parameters:
    position The number of places to shift.

These should be self-explanatory.

Definition at line 857 of file bitset.

  template<size_t _Nb> 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 1013 of file bitset.

  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 1009 of file bitset.

  template<size_t _Nb> bitset<_Nb>& std::bitset< _Nb >::operator^= (const bitset< _Nb > & __rhs) [inline]

Operations on bitsets.

Parameters:
    rhs A same-sized bitset.

These should be self-explanatory.

Definition at line 829 of file bitset.

  template<size_t _Nb> bitset<_Nb>& std::bitset< _Nb >::operator|= (const bitset< _Nb > & __rhs) [inline]

Operations on bitsets.

Parameters:
    rhs A same-sized bitset.

These should be self-explanatory.

Definition at line 822 of file bitset.

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

See the no-argument flip().

Definition at line 990 of file bitset.

  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 957 of file bitset.

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

Sets every bit to false.

Definition at line 943 of file bitset.

  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 932 of file bitset.

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

Sets every bit to true.

Definition at line 918 of file bitset.

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

Returns the total number of bits.

Definition at line 1140 of file bitset.

  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 1161 of file bitset.

  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 1037 of file bitset.

  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 1024 of file bitset.

Author

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