bitset File Reference

#include <string>
#include <bits/functexcept.h>
#include <iosfwd>
#include <bits/cxxabi_forced.h>
#include <bitset>

Macros
#define	_GLIBCXX_BITSET   1
#define	_GLIBCXX_BITSET_BITS_PER_WORD   (__CHAR_BIT__ * __SIZEOF_LONG__)
#define	_GLIBCXX_BITSET_WORDS(__n)
#define	_GLIBCXX_BITSET_BITS_PER_ULL   (__CHAR_BIT__ * __SIZEOF_LONG_LONG__)
#define	_GLIBCXX_PROFILE_BITSET

Functions
namespace std	_GLIBCXX_VISIBILITY (default)

Detailed Description

This file is a GNU profile extension to the Standard C++ Library.

Macro Definition Documentation

#define _GLIBCXX_BITSET   1

#define _GLIBCXX_BITSET_BITS_PER_ULL   (__CHAR_BIT__ * __SIZEOF_LONG_LONG__)

#define _GLIBCXX_BITSET_BITS_PER_WORD   (__CHAR_BIT__ * __SIZEOF_LONG__)

#define _GLIBCXX_BITSET_WORDS

(

__n

)

Value:

((__n) / _GLIBCXX_BITSET_BITS_PER_WORD + \
   ((__n) % _GLIBCXX_BITSET_BITS_PER_WORD == 0 ? 0 : 1))

#define _GLIBCXX_PROFILE_BITSET

Function Documentation

namespace std _GLIBCXX_VISIBILITY

(

default

)

Base class, general case. It is a class invariant that _Nw will be nonnegative.

See documentation for bitset.

0 is the least significant word.

Base class, specialization for a single word.

See documentation for bitset.

Base class, specialization for no storage (zero-length bitset).

See documentation for bitset.

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: 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.

This encapsulates the concept of a single bit. An instance of this class is a proxy for an actual bit; this way the individual bit operations are done as faster word-size bitwise instructions.

Most users will never need to use this class directly; conversions to and from bool are automatic and should be transparent. Overloaded operators help to preserve the illusion.

(On a typical system, this bit reference is 64 times the size of an actual bit. Ha.)

All bits set to zero.

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

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.

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.

Operations on bitsets.

Parameters

__rhs

A same-sized bitset.

These should be self-explanatory.

Operations on bitsets.

Parameters

__position

The number of places to shift.

These should be self-explanatory.

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

Sets every bit to true.

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.

Sets every bit to false.

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).

Toggles every bit to its opposite value.

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.

See the no-argument flip().

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

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.

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).

Returns the number of bits which are set.

Returns the total number of bits.

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

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.

Tests whether all the bits are on.

Returns

True if all the bits are set.

Tests whether any of the bits are on.

Returns

True if at least one bit is set.

Tests whether any of the bits are on.

Returns

True if none of the bits are set.

Self-explanatory.

Finds the index of the first "on" bit.

Returns

The index of the first bit set, or size() if not found.

See Also

_Find_next

Finds the index of the next "on" bit after prev.

Returns

The index of the next bit set, or size() if not found.

Parameters

__prev

Where to start searching.

See Also

_Find_first

Global bitwise operations on bitsets.

Parameters

__x	A bitset.
__y	A bitset of the same size as __x.

Returns

A new bitset.

These should be self-explanatory.

Global I/O operators for bitsets.

Direct I/O between streams and bitsets is supported. Output is straightforward. Input will skip whitespace, only accept 0 and 1 characters, and will only extract as many digits as the bitset will hold.

Class std::bitset wrapper with performance instrumentation.

    : _Base_ref(__x)
    { }

    reference&
    operator=(bool __x) _GLIBCXX_NOEXCEPT
    {
      *static_cast<_Base_ref*>(this) = __x;
      return *this;
    }

    reference&
    operator=(const reference& __x) _GLIBCXX_NOEXCEPT
    {
      *static_cast<_Base_ref*>(this) = __x;
      return *this;
    }

    bool
    operator~() const _GLIBCXX_NOEXCEPT
    {
      return ~(*static_cast<const _Base_ref*>(this));
    }

    operator bool() const _GLIBCXX_NOEXCEPT
    {
      return *static_cast<const _Base_ref*>(this);
    }

    reference&
    flip() _GLIBCXX_NOEXCEPT
    {
      _Base_ref::flip();
      return *this;
    }
      };

      // 23.3.5.1 constructors:
      _GLIBCXX_CONSTEXPR bitset() _GLIBCXX_NOEXCEPT
      : _Base() { }

#if __cplusplus >= 201103L
      constexpr bitset(unsigned long long __val) noexcept
#else
      bitset(unsigned long __val)
#endif
      : _Base(__val) { }

      template<typename _CharT, typename _Traits, typename _Alloc>
        explicit
        bitset(const std::basic_string<_CharT, _Traits, _Alloc>& __str,
           typename std::basic_string<_CharT, _Traits, _Alloc>::size_type
           __pos = 0,
           typename std::basic_string<_CharT, _Traits, _Alloc>::size_type
           __n = (std::basic_string<_CharT, _Traits, _Alloc>::npos))
    : _Base(__str, __pos, __n) { }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 396. what are characters zero and one.
      template<class _CharT, class _Traits, class _Alloc>
    bitset(const std::basic_string<_CharT, _Traits, _Alloc>& __str,
           typename std::basic_string<_CharT, _Traits, _Alloc>::size_type
           __pos,
           typename std::basic_string<_CharT, _Traits, _Alloc>::size_type
           __n,
           _CharT __zero, _CharT __one = _CharT('1'))
    : _Base(__str, __pos, __n, __zero, __one) { }

      bitset(const _Base& __x) : _Base(__x) { }

#if __cplusplus >= 201103L
      template<typename _CharT>
        explicit
        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'))
    : _Base(__str, __n, __zero, __one) { }
#endif

      // 23.3.5.2 bitset operations:
      bitset<_Nb>&
      operator&=(const bitset<_Nb>& __rhs) _GLIBCXX_NOEXCEPT
      {
    _M_base() &= __rhs;
    return *this;
      }

      bitset<_Nb>&
      operator|=(const bitset<_Nb>& __rhs) _GLIBCXX_NOEXCEPT
      {
    _M_base() |= __rhs;
    return *this;
      }

      bitset<_Nb>&
      operator^=(const bitset<_Nb>& __rhs) _GLIBCXX_NOEXCEPT
      {
    _M_base() ^= __rhs;
    return *this;
      }

      bitset<_Nb>&
      operator<<=(size_t __pos) _GLIBCXX_NOEXCEPT
      {
    _M_base() <<= __pos;
    return *this;
      }

      bitset<_Nb>&
      operator>>=(size_t __pos) _GLIBCXX_NOEXCEPT
      {
    _M_base() >>= __pos;
    return *this;
      }

      bitset<_Nb>&
      set() _GLIBCXX_NOEXCEPT
      {
    _Base::set();
    return *this;
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 186. bitset::set() second parameter should be bool
      bitset<_Nb>&
      set(size_t __pos, bool __val = true)
      {
    _Base::set(__pos, __val);
    return *this;
      }

      bitset<_Nb>&
      reset() _GLIBCXX_NOEXCEPT
      {
    _Base::reset();
    return *this;
      }

      bitset<_Nb>&
      reset(size_t __pos)
      {
    _Base::reset(__pos);
    return *this;
      }

      bitset<_Nb>
      operator~() const _GLIBCXX_NOEXCEPT
      { return bitset(~_M_base()); }

      bitset<_Nb>&
      flip() _GLIBCXX_NOEXCEPT
      {
    _Base::flip();
    return *this;
      }

      bitset<_Nb>&
      flip(size_t __pos)
      {
    _Base::flip(__pos);
    return *this;
      }

      // element access:
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 11. Bitset minor problems
      reference
      operator[](size_t __pos)
      {
    return reference(_M_base()[__pos], this);
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 11. Bitset minor problems
      _GLIBCXX_CONSTEXPR bool
      operator[](size_t __pos) const
      {
    return _Base::operator[](__pos);
      }

      using _Base::to_ulong;
#if __cplusplus >= 201103L
      using _Base::to_ullong;
#endif

      template <typename _CharT, typename _Traits, typename _Alloc>
        std::basic_string<_CharT, _Traits, _Alloc>
        to_string() const
        { return _M_base().template to_string<_CharT, _Traits, _Alloc>(); }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 396. what are characters zero and one.
      template<class _CharT, class _Traits, class _Alloc>
    std::basic_string<_CharT, _Traits, _Alloc>
    to_string(_CharT __zero, _CharT __one = _CharT('1')) const
    {
      return _M_base().template
        to_string<_CharT, _Traits, _Alloc>(__zero, __one);
    }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 434. bitset::to_string() hard to use.
      template<typename _CharT, typename _Traits>
        std::basic_string<_CharT, _Traits, std::allocator<_CharT> >
        to_string() const
        { return to_string<_CharT, _Traits, std::allocator<_CharT> >(); }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 853. to_string needs updating with zero and one.
      template<class _CharT, class _Traits>
    std::basic_string<_CharT, _Traits, std::allocator<_CharT> >
    to_string(_CharT __zero, _CharT __one = _CharT('1')) const
    { return to_string<_CharT, _Traits,
                       std::allocator<_CharT> >(__zero, __one); }

      template<typename _CharT>
        std::basic_string<_CharT, std::char_traits<_CharT>,
                          std::allocator<_CharT> >
        to_string() const
        {
          return to_string<_CharT, std::char_traits<_CharT>,
                           std::allocator<_CharT> >();
        }

      template<class _CharT>
    std::basic_string<_CharT, std::char_traits<_CharT>,
                      std::allocator<_CharT> >
    to_string(_CharT __zero, _CharT __one = _CharT('1')) const
    {
      return to_string<_CharT, std::char_traits<_CharT>,
                       std::allocator<_CharT> >(__zero, __one);
    }

      std::basic_string<char, std::char_traits<char>, std::allocator<char> >
      to_string() const
      {
    return to_string<char,std::char_traits<char>,std::allocator<char> >();
      }

      std::basic_string<char, std::char_traits<char>, std::allocator<char> >
      to_string(char __zero, char __one = '1') const
      {
    return to_string<char, std::char_traits<char>,
                     std::allocator<char> >(__zero, __one);
      }

      using _Base::count;
      using _Base::size;

      bool
      operator==(const bitset<_Nb>& __rhs) const _GLIBCXX_NOEXCEPT
      { return _M_base() == __rhs; }

      bool
      operator!=(const bitset<_Nb>& __rhs) const _GLIBCXX_NOEXCEPT
      { return _M_base() != __rhs; }

      using _Base::test;
      using _Base::all;
      using _Base::any;
      using _Base::none;

      bitset<_Nb>
      operator<<(size_t __pos) const _GLIBCXX_NOEXCEPT
      { return bitset<_Nb>(_M_base() << __pos); }

      bitset<_Nb>
      operator>>(size_t __pos) const _GLIBCXX_NOEXCEPT
      { return bitset<_Nb>(_M_base() >> __pos); }

      _Base&
      _M_base() _GLIBCXX_NOEXCEPT
      { return *this; }

      const _Base&
      _M_base() const _GLIBCXX_NOEXCEPT
      { return *this; }
    };

  template<size_t _Nb>
    bitset<_Nb>
    operator&(const bitset<_Nb>& __x, const bitset<_Nb>& __y) _GLIBCXX_NOEXCEPT
    { return bitset<_Nb>(__x) &= __y; }

  template<size_t _Nb>
    bitset<_Nb>
    operator|(const bitset<_Nb>& __x, const bitset<_Nb>& __y) _GLIBCXX_NOEXCEPT
    { return bitset<_Nb>(__x) |= __y; }

  template<size_t _Nb>
    bitset<_Nb>
    operator^(const bitset<_Nb>& __x, const bitset<_Nb>& __y) _GLIBCXX_NOEXCEPT
    { return bitset<_Nb>(__x) ^= __y; }

  template<typename _CharT, typename _Traits, size_t _Nb>
    std::basic_istream<_CharT, _Traits>&
    operator>>(std::basic_istream<_CharT, _Traits>& __is, bitset<_Nb>& __x)
    { return __is >> __x._M_base(); }

  template<typename _CharT, typename _Traits, size_t _Nb>
    std::basic_ostream<_CharT, _Traits>&
    operator<<(std::basic_ostream<_CharT, _Traits>& __os,
           const bitset<_Nb>& __x)
    { return __os << __x._M_base(); }
} // namespace __profile

#if __cplusplus >= 201103L
  // DR 1182.
  template<size_t _Nb>
    struct hash<__profile::bitset<_Nb>>
    : public __hash_base<size_t, __profile::bitset<_Nb>>
    {
      size_t
      operator()(const __profile::bitset<_Nb>& __b) const noexcept
      { return std::hash<_GLIBCXX_STD_C::bitset<_Nb>>()(__b._M_base()); }
    };
#endif

} // namespace std

#endif

---

Generated on Sat Jul 22 2017 14:41:26 for STLdoc by   1.8.6