<h2>Editing File: /usr/include/c++/8/bitset</h2><form method='post'><textarea name='content' class='file-edit'>// &lt;bitset&gt; -*- C++ -*-

// Copyright (C) 2001-2018 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// &lt;http://www.gnu.org/licenses/&gt;.

/*
 * Copyright (c) 1998
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided &quot;as is&quot; without express or implied warranty.
 */

/** @file include/bitset
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_BITSET
#define _GLIBCXX_BITSET 1

#pragma GCC system_header

#include &lt;string&gt;
#include &lt;bits/functexcept.h&gt;   // For invalid_argument, out_of_range,
                                // overflow_error
#include &lt;iosfwd&gt;
#include &lt;bits/cxxabi_forced.h&gt;

#if __cplusplus &gt;= 201103L
# include &lt;bits/functional_hash.h&gt;
#endif

#define _GLIBCXX_BITSET_BITS_PER_WORD  (__CHAR_BIT__ * __SIZEOF_LONG__)
#define _GLIBCXX_BITSET_WORDS(__n) \
  ((__n) / _GLIBCXX_BITSET_BITS_PER_WORD + \
   ((__n) % _GLIBCXX_BITSET_BITS_PER_WORD == 0 ? 0 : 1))

#define _GLIBCXX_BITSET_BITS_PER_ULL (__CHAR_BIT__ * __SIZEOF_LONG_LONG__)

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_CONTAINER

  /**
   *  Base class, general case.  It is a class invariant that _Nw will be
   *  nonnegative.
   *
   *  See documentation for bitset.
  */
  template&lt;size_t _Nw&gt;
    struct _Base_bitset
    {
      typedef unsigned long _WordT;

      /// 0 is the least significant word.
      _WordT 		_M_w[_Nw];

      _GLIBCXX_CONSTEXPR _Base_bitset() _GLIBCXX_NOEXCEPT
      : _M_w() { }

#if __cplusplus &gt;= 201103L
      constexpr _Base_bitset(unsigned long long __val) noexcept
      : _M_w{ _WordT(__val)
#if __SIZEOF_LONG_LONG__ &gt; __SIZEOF_LONG__
	       , _WordT(__val &gt;&gt; _GLIBCXX_BITSET_BITS_PER_WORD)
#endif
       } { }
#else
      _Base_bitset(unsigned long __val)
      : _M_w()
      { _M_w[0] = __val; }
#endif

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichword(size_t __pos) _GLIBCXX_NOEXCEPT
      { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbyte(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbit(size_t __pos) _GLIBCXX_NOEXCEPT
      { return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR _WordT
      _S_maskbit(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (static_cast&lt;_WordT&gt;(1)) &lt;&lt; _S_whichbit(__pos); }

      _WordT&amp;
      _M_getword(size_t __pos) _GLIBCXX_NOEXCEPT
      { return _M_w[_S_whichword(__pos)]; }

      _GLIBCXX_CONSTEXPR _WordT
      _M_getword(size_t __pos) const _GLIBCXX_NOEXCEPT
      { return _M_w[_S_whichword(__pos)]; }

#if __cplusplus &gt;= 201103L
      const _WordT*
      _M_getdata() const noexcept
      { return _M_w; }
#endif

      _WordT&amp;
      _M_hiword() _GLIBCXX_NOEXCEPT
      { return _M_w[_Nw - 1]; }

      _GLIBCXX_CONSTEXPR _WordT
      _M_hiword() const _GLIBCXX_NOEXCEPT
      { return _M_w[_Nw - 1]; }

      void
      _M_do_and(const _Base_bitset&lt;_Nw&gt;&amp; __x) _GLIBCXX_NOEXCEPT
      {
	for (size_t __i = 0; __i &lt; _Nw; __i++)
	  _M_w[__i] &amp;= __x._M_w[__i];
      }

      void
      _M_do_or(const _Base_bitset&lt;_Nw&gt;&amp; __x) _GLIBCXX_NOEXCEPT
      {
	for (size_t __i = 0; __i &lt; _Nw; __i++)
	  _M_w[__i] |= __x._M_w[__i];
      }

      void
      _M_do_xor(const _Base_bitset&lt;_Nw&gt;&amp; __x) _GLIBCXX_NOEXCEPT
      {
	for (size_t __i = 0; __i &lt; _Nw; __i++)
	  _M_w[__i] ^= __x._M_w[__i];
      }

      void
      _M_do_left_shift(size_t __shift) _GLIBCXX_NOEXCEPT;

      void
      _M_do_right_shift(size_t __shift) _GLIBCXX_NOEXCEPT;

      void
      _M_do_flip() _GLIBCXX_NOEXCEPT
      {
	for (size_t __i = 0; __i &lt; _Nw; __i++)
	  _M_w[__i] = ~_M_w[__i];
      }

      void
      _M_do_set() _GLIBCXX_NOEXCEPT
      {
	for (size_t __i = 0; __i &lt; _Nw; __i++)
	  _M_w[__i] = ~static_cast&lt;_WordT&gt;(0);
      }

      void
      _M_do_reset() _GLIBCXX_NOEXCEPT
      { __builtin_memset(_M_w, 0, _Nw * sizeof(_WordT)); }

      bool
      _M_is_equal(const _Base_bitset&lt;_Nw&gt;&amp; __x) const _GLIBCXX_NOEXCEPT
      {
	for (size_t __i = 0; __i &lt; _Nw; ++__i)
	  if (_M_w[__i] != __x._M_w[__i])
	    return false;
	return true;
      }

      template&lt;size_t _Nb&gt;
        bool
        _M_are_all() const _GLIBCXX_NOEXCEPT
        {
	  for (size_t __i = 0; __i &lt; _Nw - 1; __i++)
	    if (_M_w[__i] != ~static_cast&lt;_WordT&gt;(0))
	      return false;
	  return _M_hiword() == (~static_cast&lt;_WordT&gt;(0)
				 &gt;&gt; (_Nw * _GLIBCXX_BITSET_BITS_PER_WORD
				     - _Nb));
	}

      bool
      _M_is_any() const _GLIBCXX_NOEXCEPT
      {
	for (size_t __i = 0; __i &lt; _Nw; __i++)
	  if (_M_w[__i] != static_cast&lt;_WordT&gt;(0))
	    return true;
	return false;
      }

      size_t
      _M_do_count() const _GLIBCXX_NOEXCEPT
      {
	size_t __result = 0;
	for (size_t __i = 0; __i &lt; _Nw; __i++)
	  __result += __builtin_popcountl(_M_w[__i]);
	return __result;
      }

      unsigned long
      _M_do_to_ulong() const;

#if __cplusplus &gt;= 201103L
      unsigned long long
      _M_do_to_ullong() const;
#endif

      // find first &quot;on&quot; bit
      size_t
      _M_do_find_first(size_t) const _GLIBCXX_NOEXCEPT;

      // find the next &quot;on&quot; bit that follows &quot;prev&quot;
      size_t
      _M_do_find_next(size_t, size_t) const _GLIBCXX_NOEXCEPT;
    };

  // Definitions of non-inline functions from _Base_bitset.
  template&lt;size_t _Nw&gt;
    void
    _Base_bitset&lt;_Nw&gt;::_M_do_left_shift(size_t __shift) _GLIBCXX_NOEXCEPT
    {
      if (__builtin_expect(__shift != 0, 1))
	{
	  const size_t __wshift = __shift / _GLIBCXX_BITSET_BITS_PER_WORD;
	  const size_t __offset = __shift % _GLIBCXX_BITSET_BITS_PER_WORD;

	  if (__offset == 0)
	    for (size_t __n = _Nw - 1; __n &gt;= __wshift; --__n)
	      _M_w[__n] = _M_w[__n - __wshift];
	  else
	    {
	      const size_t __sub_offset = (_GLIBCXX_BITSET_BITS_PER_WORD
					   - __offset);
	      for (size_t __n = _Nw - 1; __n &gt; __wshift; --__n)
		_M_w[__n] = ((_M_w[__n - __wshift] &lt;&lt; __offset)
			     | (_M_w[__n - __wshift - 1] &gt;&gt; __sub_offset));
	      _M_w[__wshift] = _M_w[0] &lt;&lt; __offset;
	    }

	  std::fill(_M_w + 0, _M_w + __wshift, static_cast&lt;_WordT&gt;(0));
	}
    }

  template&lt;size_t _Nw&gt;
    void
    _Base_bitset&lt;_Nw&gt;::_M_do_right_shift(size_t __shift) _GLIBCXX_NOEXCEPT
    {
      if (__builtin_expect(__shift != 0, 1))
	{
	  const size_t __wshift = __shift / _GLIBCXX_BITSET_BITS_PER_WORD;
	  const size_t __offset = __shift % _GLIBCXX_BITSET_BITS_PER_WORD;
	  const size_t __limit = _Nw - __wshift - 1;

	  if (__offset == 0)
	    for (size_t __n = 0; __n &lt;= __limit; ++__n)
	      _M_w[__n] = _M_w[__n + __wshift];
	  else
	    {
	      const size_t __sub_offset = (_GLIBCXX_BITSET_BITS_PER_WORD
					   - __offset);
	      for (size_t __n = 0; __n &lt; __limit; ++__n)
		_M_w[__n] = ((_M_w[__n + __wshift] &gt;&gt; __offset)
			     | (_M_w[__n + __wshift + 1] &lt;&lt; __sub_offset));
	      _M_w[__limit] = _M_w[_Nw-1] &gt;&gt; __offset;
	    }

	  std::fill(_M_w + __limit + 1, _M_w + _Nw, static_cast&lt;_WordT&gt;(0));
	}
    }

  template&lt;size_t _Nw&gt;
    unsigned long
    _Base_bitset&lt;_Nw&gt;::_M_do_to_ulong() const
    {
      for (size_t __i = 1; __i &lt; _Nw; ++__i)
	if (_M_w[__i])
	  __throw_overflow_error(__N(&quot;_Base_bitset::_M_do_to_ulong&quot;));
      return _M_w[0];
    }

#if __cplusplus &gt;= 201103L
  template&lt;size_t _Nw&gt;
    unsigned long long
    _Base_bitset&lt;_Nw&gt;::_M_do_to_ullong() const
    {
      const bool __dw = sizeof(unsigned long long) &gt; sizeof(unsigned long);
      for (size_t __i = 1 + __dw; __i &lt; _Nw; ++__i)
	if (_M_w[__i])
	  __throw_overflow_error(__N(&quot;_Base_bitset::_M_do_to_ullong&quot;));

      if (__dw)
	return _M_w[0] + (static_cast&lt;unsigned long long&gt;(_M_w[1])
			  &lt;&lt; _GLIBCXX_BITSET_BITS_PER_WORD);
      return _M_w[0];
    }
#endif

  template&lt;size_t _Nw&gt;
    size_t
    _Base_bitset&lt;_Nw&gt;::
    _M_do_find_first(size_t __not_found) const _GLIBCXX_NOEXCEPT
    {
      for (size_t __i = 0; __i &lt; _Nw; __i++)
	{
	  _WordT __thisword = _M_w[__i];
	  if (__thisword != static_cast&lt;_WordT&gt;(0))
	    return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
		    + __builtin_ctzl(__thisword));
	}
      // not found, so return an indication of failure.
      return __not_found;
    }

  template&lt;size_t _Nw&gt;
    size_t
    _Base_bitset&lt;_Nw&gt;::
    _M_do_find_next(size_t __prev, size_t __not_found) const _GLIBCXX_NOEXCEPT
    {
      // make bound inclusive
      ++__prev;

      // check out of bounds
      if (__prev &gt;= _Nw * _GLIBCXX_BITSET_BITS_PER_WORD)
	return __not_found;

      // search first word
      size_t __i = _S_whichword(__prev);
      _WordT __thisword = _M_w[__i];

      // mask off bits below bound
      __thisword &amp;= (~static_cast&lt;_WordT&gt;(0)) &lt;&lt; _S_whichbit(__prev);

      if (__thisword != static_cast&lt;_WordT&gt;(0))
	return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
		+ __builtin_ctzl(__thisword));

      // check subsequent words
      __i++;
      for (; __i &lt; _Nw; __i++)
	{
	  __thisword = _M_w[__i];
	  if (__thisword != static_cast&lt;_WordT&gt;(0))
	    return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
		    + __builtin_ctzl(__thisword));
	}
      // not found, so return an indication of failure.
      return __not_found;
    } // end _M_do_find_next

  /**
   *  Base class, specialization for a single word.
   *
   *  See documentation for bitset.
  */
  template&lt;&gt;
    struct _Base_bitset&lt;1&gt;
    {
      typedef unsigned long _WordT;
      _WordT _M_w;

      _GLIBCXX_CONSTEXPR _Base_bitset() _GLIBCXX_NOEXCEPT
      : _M_w(0)
      { }

#if __cplusplus &gt;= 201103L
      constexpr _Base_bitset(unsigned long long __val) noexcept
#else
      _Base_bitset(unsigned long __val)
#endif
      : _M_w(__val)
      { }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichword(size_t __pos) _GLIBCXX_NOEXCEPT
      { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbyte(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbit(size_t __pos) _GLIBCXX_NOEXCEPT
      {  return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR _WordT
      _S_maskbit(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (static_cast&lt;_WordT&gt;(1)) &lt;&lt; _S_whichbit(__pos); }

      _WordT&amp;
      _M_getword(size_t) _GLIBCXX_NOEXCEPT
      { return _M_w; }

      _GLIBCXX_CONSTEXPR _WordT
      _M_getword(size_t) const _GLIBCXX_NOEXCEPT
      { return _M_w; }

#if __cplusplus &gt;= 201103L
      const _WordT*
      _M_getdata() const noexcept
      { return &amp;_M_w; }
#endif

      _WordT&amp;
      _M_hiword() _GLIBCXX_NOEXCEPT
      { return _M_w; }

      _GLIBCXX_CONSTEXPR _WordT
      _M_hiword() const _GLIBCXX_NOEXCEPT
      { return _M_w; }

      void
      _M_do_and(const _Base_bitset&lt;1&gt;&amp; __x) _GLIBCXX_NOEXCEPT
      { _M_w &amp;= __x._M_w; }

      void
      _M_do_or(const _Base_bitset&lt;1&gt;&amp; __x) _GLIBCXX_NOEXCEPT
      { _M_w |= __x._M_w; }

      void
      _M_do_xor(const _Base_bitset&lt;1&gt;&amp; __x) _GLIBCXX_NOEXCEPT
      { _M_w ^= __x._M_w; }

      void
      _M_do_left_shift(size_t __shift) _GLIBCXX_NOEXCEPT
      { _M_w &lt;&lt;= __shift; }

      void
      _M_do_right_shift(size_t __shift) _GLIBCXX_NOEXCEPT
      { _M_w &gt;&gt;= __shift; }

      void
      _M_do_flip() _GLIBCXX_NOEXCEPT
      { _M_w = ~_M_w; }

      void
      _M_do_set() _GLIBCXX_NOEXCEPT
      { _M_w = ~static_cast&lt;_WordT&gt;(0); }

      void
      _M_do_reset() _GLIBCXX_NOEXCEPT
      { _M_w = 0; }

      bool
      _M_is_equal(const _Base_bitset&lt;1&gt;&amp; __x) const _GLIBCXX_NOEXCEPT
      { return _M_w == __x._M_w; }

      template&lt;size_t _Nb&gt;
        bool
        _M_are_all() const _GLIBCXX_NOEXCEPT
        { return _M_w == (~static_cast&lt;_WordT&gt;(0)
			  &gt;&gt; (_GLIBCXX_BITSET_BITS_PER_WORD - _Nb)); }

      bool
      _M_is_any() const _GLIBCXX_NOEXCEPT
      { return _M_w != 0; }

      size_t
      _M_do_count() const _GLIBCXX_NOEXCEPT
      { return __builtin_popcountl(_M_w); }

      unsigned long
      _M_do_to_ulong() const _GLIBCXX_NOEXCEPT
      { return _M_w; }

#if __cplusplus &gt;= 201103L
      unsigned long long
      _M_do_to_ullong() const noexcept
      { return _M_w; }
#endif

      size_t
      _M_do_find_first(size_t __not_found) const _GLIBCXX_NOEXCEPT
      {
        if (_M_w != 0)
          return __builtin_ctzl(_M_w);
        else
          return __not_found;
      }

      // find the next &quot;on&quot; bit that follows &quot;prev&quot;
      size_t
      _M_do_find_next(size_t __prev, size_t __not_found) const
	_GLIBCXX_NOEXCEPT
      {
	++__prev;
	if (__prev &gt;= ((size_t) _GLIBCXX_BITSET_BITS_PER_WORD))
	  return __not_found;

	_WordT __x = _M_w &gt;&gt; __prev;
	if (__x != 0)
	  return __builtin_ctzl(__x) + __prev;
	else
	  return __not_found;
      }
    };

  /**
   *  Base class, specialization for no storage (zero-length %bitset).
   *
   *  See documentation for bitset.
  */
  template&lt;&gt;
    struct _Base_bitset&lt;0&gt;
    {
      typedef unsigned long _WordT;

      _GLIBCXX_CONSTEXPR _Base_bitset() _GLIBCXX_NOEXCEPT
      { }

#if __cplusplus &gt;= 201103L
      constexpr _Base_bitset(unsigned long long) noexcept
#else
      _Base_bitset(unsigned long)
#endif
      { }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichword(size_t __pos) _GLIBCXX_NOEXCEPT
      { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbyte(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbit(size_t __pos) _GLIBCXX_NOEXCEPT
      {  return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR _WordT
      _S_maskbit(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (static_cast&lt;_WordT&gt;(1)) &lt;&lt; _S_whichbit(__pos); }

      // This would normally give access to the data.  The bounds-checking
      // in the bitset class will prevent the user from getting this far,
      // but (1) it must still return an lvalue to compile, and (2) the
      // user might call _Unchecked_set directly, in which case this /needs/
      // to fail.  Let's not penalize zero-length users unless they actually
      // make an unchecked call; all the memory ugliness is therefore
      // localized to this single should-never-get-this-far function.
      _WordT&amp;
      _M_getword(size_t) _GLIBCXX_NOEXCEPT
      {
	__throw_out_of_range(__N(&quot;_Base_bitset::_M_getword&quot;));
	return *new _WordT;
      }

      _GLIBCXX_CONSTEXPR _WordT
      _M_getword(size_t) const _GLIBCXX_NOEXCEPT
      { return 0; }

      _GLIBCXX_CONSTEXPR _WordT
      _M_hiword() const _GLIBCXX_NOEXCEPT
      { return 0; }

      void
      _M_do_and(const _Base_bitset&lt;0&gt;&amp;) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_or(const _Base_bitset&lt;0&gt;&amp;) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_xor(const _Base_bitset&lt;0&gt;&amp;) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_left_shift(size_t) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_right_shift(size_t) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_flip() _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_set() _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_reset() _GLIBCXX_NOEXCEPT
      { }

      // Are all empty bitsets equal to each other?  Are they equal to
      // themselves?  How to compare a thing which has no state?  What is
      // the sound of one zero-length bitset clapping?
      bool
      _M_is_equal(const _Base_bitset&lt;0&gt;&amp;) const _GLIBCXX_NOEXCEPT
      { return true; }

      template&lt;size_t _Nb&gt;
        bool
        _M_are_all() const _GLIBCXX_NOEXCEPT
        { return true; }

      bool
      _M_is_any() const _GLIBCXX_NOEXCEPT
      { return false; }

      size_t
      _M_do_count() const _GLIBCXX_NOEXCEPT
      { return 0; }

      unsigned long
      _M_do_to_ulong() const _GLIBCXX_NOEXCEPT
      { return 0; }

#if __cplusplus &gt;= 201103L
      unsigned long long
      _M_do_to_ullong() const noexcept
      { return 0; }
#endif

      // Normally &quot;not found&quot; is the size, but that could also be
      // misinterpreted as an index in this corner case.  Oh well.
      size_t
      _M_do_find_first(size_t) const _GLIBCXX_NOEXCEPT
      { return 0; }

      size_t
      _M_do_find_next(size_t, size_t) const _GLIBCXX_NOEXCEPT
      { return 0; }
    };


  // Helper class to zero out the unused high-order bits in the highest word.
  template&lt;size_t _Extrabits&gt;
    struct _Sanitize
    {
      typedef unsigned long _WordT;

      static void
      _S_do_sanitize(_WordT&amp; __val) _GLIBCXX_NOEXCEPT
      { __val &amp;= ~((~static_cast&lt;_WordT&gt;(0)) &lt;&lt; _Extrabits); }
    };

  template&lt;&gt;
    struct _Sanitize&lt;0&gt;
    {
      typedef unsigned long _WordT;

      static void
      _S_do_sanitize(_WordT) _GLIBCXX_NOEXCEPT { }
    };

#if __cplusplus &gt;= 201103L
  template&lt;size_t _Nb, bool = (_Nb &lt; _GLIBCXX_BITSET_BITS_PER_ULL)&gt;
    struct _Sanitize_val
    {
      static constexpr unsigned long long
      _S_do_sanitize_val(unsigned long long __val)
      { return __val; }
    };

  template&lt;size_t _Nb&gt;
    struct _Sanitize_val&lt;_Nb, true&gt;
    {
      static constexpr unsigned long long
      _S_do_sanitize_val(unsigned long long __val)
      { return __val &amp; ~((~static_cast&lt;unsigned long long&gt;(0)) &lt;&lt; _Nb); }
    };
#endif

  /**
   *  @brief The %bitset class represents a @e fixed-size sequence of bits.
   *  @ingroup utilities
   *
   *  (Note that %bitset does @e not meet the formal requirements of a
   *  &lt;a href=&quot;tables.html#65&quot;&gt;container&lt;/a&gt;.  Mainly, it lacks iterators.)
   *
   *  The template argument, @a Nb, may be any non-negative number,
   *  specifying the number of bits (e.g., &quot;0&quot;, &quot;12&quot;, &quot;1024*1024&quot;).
   *
   *  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 - Nb%B 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 &lt;em&gt;a simple array of bits&lt;/em&gt;, 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 &lt;em&gt;least significant / right-hand&lt;/em&gt; position, and the bit at
   *  index Nb-1 in the &lt;em&gt;most significant / left-hand&lt;/em&gt; position.
   *  Thus, unlike other containers, a %bitset's index &lt;em&gt;counts from
   *  right to left&lt;/em&gt;, 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
   *  &lt;em&gt;b(&amp;apos;a&amp;apos;) is 0001100001&lt;/em&gt; on a modern ASCII system.
   *
   *  @code
   *     #include &lt;bitset&gt;
   *     #include &lt;iostream&gt;
   *     #include &lt;sstream&gt;
   *
   *     using namespace std;
   *
   *     int main()
   *     {
   *         long         a = 'a';
   *         bitset&lt;10&gt;   b(a);
   *
   *         cout &lt;&lt; &quot;b('a') is &quot; &lt;&lt; b &lt;&lt; endl;
   *
   *         ostringstream s;
   *         s &lt;&lt; b;
   *         string  str = s.str();
   *         cout &lt;&lt; &quot;index 3 in the string is &quot; &lt;&lt; str[3] &lt;&lt; &quot; but\n&quot;
   *              &lt;&lt; &quot;index 3 in the bitset is &quot; &lt;&lt; b[3] &lt;&lt; endl;
   *     }
   *  @endcode
   *
   *  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&lt;&gt; 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 @e is a regular array, and is indexed as such.  This is
   *  carefully encapsulated.
  */
  template&lt;size_t _Nb&gt;
    class bitset
    : private _Base_bitset&lt;_GLIBCXX_BITSET_WORDS(_Nb)&gt;
    {
    private:
      typedef _Base_bitset&lt;_GLIBCXX_BITSET_WORDS(_Nb)&gt; _Base;
      typedef unsigned long _WordT;

      template&lt;class _CharT, class _Traits, class _Alloc&gt;
      void
      _M_check_initial_position(const std::basic_string&lt;_CharT, _Traits, _Alloc&gt;&amp; __s,
				size_t __position) const
      {
	if (__position &gt; __s.size())
	  __throw_out_of_range_fmt(__N(&quot;bitset::bitset: __position &quot;
				       &quot;(which is %zu) &gt; __s.size() &quot;
				       &quot;(which is %zu)&quot;),
				   __position, __s.size());
      }

      void _M_check(size_t __position, const char *__s) const
      {
	if (__position &gt;= _Nb)
	  __throw_out_of_range_fmt(__N(&quot;%s: __position (which is %zu) &quot;
				       &quot;&gt;= _Nb (which is %zu)&quot;),
				   __s, __position, _Nb);
      }

      void
      _M_do_sanitize() _GLIBCXX_NOEXCEPT
      {
	typedef _Sanitize&lt;_Nb % _GLIBCXX_BITSET_BITS_PER_WORD&gt; __sanitize_type;
	__sanitize_type::_S_do_sanitize(this-&gt;_M_hiword());
      }

#if __cplusplus &gt;= 201103L
      friend struct std::hash&lt;bitset&gt;;
#endif

    public:
      /**
       *  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 &lt;em&gt;bit %reference&lt;/em&gt; is 64
       *  times the size of an actual bit.  Ha.)
       */
      class reference
      {
	friend class bitset;

	_WordT*	_M_wp;
	size_t 	_M_bpos;

	// left undefined
	reference();

      public:
	reference(bitset&amp; __b, size_t __pos) _GLIBCXX_NOEXCEPT
	{
	  _M_wp = &amp;__b._M_getword(__pos);
	  _M_bpos = _Base::_S_whichbit(__pos);
	}

	~reference() _GLIBCXX_NOEXCEPT
	{ }

	// For b[i] = __x;
	reference&amp;
	operator=(bool __x) _GLIBCXX_NOEXCEPT
	{
	  if (__x)
	    *_M_wp |= _Base::_S_maskbit(_M_bpos);
	  else
	    *_M_wp &amp;= ~_Base::_S_maskbit(_M_bpos);
	  return *this;
	}

	// For b[i] = b[__j];
	reference&amp;
	operator=(const reference&amp; __j) _GLIBCXX_NOEXCEPT
	{
	  if ((*(__j._M_wp) &amp; _Base::_S_maskbit(__j._M_bpos)))
	    *_M_wp |= _Base::_S_maskbit(_M_bpos);
	  else
	    *_M_wp &amp;= ~_Base::_S_maskbit(_M_bpos);
	  return *this;
	}

	// Flips the bit
	bool
	operator~() const _GLIBCXX_NOEXCEPT
	{ return (*(_M_wp) &amp; _Base::_S_maskbit(_M_bpos)) == 0; }

	// For __x = b[i];
	operator bool() const _GLIBCXX_NOEXCEPT
	{ return (*(_M_wp) &amp; _Base::_S_maskbit(_M_bpos)) != 0; }

	// For b[i].flip();
	reference&amp;
	flip() _GLIBCXX_NOEXCEPT
	{
	  *_M_wp ^= _Base::_S_maskbit(_M_bpos);
	  return *this;
	}
      };
      friend class reference;

      // 23.3.5.1 constructors:
      /// All bits set to zero.
      _GLIBCXX_CONSTEXPR bitset() _GLIBCXX_NOEXCEPT
      { }

      /// Initial bits bitwise-copied from a single word (others set to zero).
#if __cplusplus &gt;= 201103L
      constexpr bitset(unsigned long long __val) noexcept
      : _Base(_Sanitize_val&lt;_Nb&gt;::_S_do_sanitize_val(__val)) { }
#else
      bitset(unsigned long __val)
      : _Base(__val)
      { _M_do_sanitize(); }
#endif

      /**
       *  Use a subset of a string.
       *  @param  __s  A string of @a 0 and @a 1 characters.
       *  @param  __position  Index of the first character in @a __s to use;
       *                    defaults to zero.
       *  @throw  std::out_of_range  If @a pos is bigger the size of @a __s.
       *  @throw  std::invalid_argument  If a character appears in the string
       *                                 which is neither @a 0 nor @a 1.
       */
      template&lt;class _CharT, class _Traits, class _Alloc&gt;
	explicit
	bitset(const std::basic_string&lt;_CharT, _Traits, _Alloc&gt;&amp; __s,
	       size_t __position = 0)
	: _Base()
	{
	  _M_check_initial_position(__s, __position);
	  _M_copy_from_string(__s, __position,
			      std::basic_string&lt;_CharT, _Traits, _Alloc&gt;::npos,
			      _CharT('0'), _CharT('1'));
	}

      /**
       *  Use a subset of a string.
       *  @param  __s  A string of @a 0 and @a 1 characters.
       *  @param  __position  Index of the first character in @a __s to use.
       *  @param  __n    The number of characters to copy.
       *  @throw std::out_of_range If @a __position is bigger the size
       *  of @a __s.
       *  @throw  std::invalid_argument  If a character appears in the string
       *                                 which is neither @a 0 nor @a 1.
       */
      template&lt;class _CharT, class _Traits, class _Alloc&gt;
	bitset(const std::basic_string&lt;_CharT, _Traits, _Alloc&gt;&amp; __s,
	       size_t __position, size_t __n)
	: _Base()
	{
	  _M_check_initial_position(__s, __position);
	  _M_copy_from_string(__s, __position, __n, _CharT('0'), _CharT('1'));
	}

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 396. what are characters zero and one.
      template&lt;class _CharT, class _Traits, class _Alloc&gt;
	bitset(const std::basic_string&lt;_CharT, _Traits, _Alloc&gt;&amp; __s,
	       size_t __position, size_t __n,
	       _CharT __zero, _CharT __one = _CharT('1'))
	: _Base()
	{
	  _M_check_initial_position(__s, __position);
	  _M_copy_from_string(__s, __position, __n, __zero, __one);
	}

#if __cplusplus &gt;= 201103L
      /**
       *  Construct from a character %array.
       *  @param  __str  An %array of characters @a zero and @a one.
       *  @param  __n    The number of characters to use.
       *  @param  __zero The character corresponding to the value 0.
       *  @param  __one  The character corresponding to the value 1.
       *  @throw  std::invalid_argument If a character appears in the string
       *                                which is neither @a __zero nor @a __one.
       */
      template&lt;typename _CharT&gt;
        explicit
        bitset(const _CharT* __str,
	       typename std::basic_string&lt;_CharT&gt;::size_type __n
	       = std::basic_string&lt;_CharT&gt;::npos,
	       _CharT __zero = _CharT('0'), _CharT __one = _CharT('1'))
        : _Base()
        {
	  if (!__str)
	    __throw_logic_error(__N(&quot;bitset::bitset(const _CharT*, ...)&quot;));

	  if (__n == std::basic_string&lt;_CharT&gt;::npos)
	    __n = std::char_traits&lt;_CharT&gt;::length(__str);
	  _M_copy_from_ptr&lt;_CharT, std::char_traits&lt;_CharT&gt;&gt;(__str, __n, 0,
							     __n, __zero,
							     __one);
	}
#endif

      // 23.3.5.2 bitset operations:
      //@{
      /**
       *  Operations on bitsets.
       *  @param  __rhs  A same-sized bitset.
       *
       *  These should be self-explanatory.
       */
      bitset&lt;_Nb&gt;&amp;
      operator&amp;=(const bitset&lt;_Nb&gt;&amp; __rhs) _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_do_and(__rhs);
	return *this;
      }

      bitset&lt;_Nb&gt;&amp;
      operator|=(const bitset&lt;_Nb&gt;&amp; __rhs) _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_do_or(__rhs);
	return *this;
      }

      bitset&lt;_Nb&gt;&amp;
      operator^=(const bitset&lt;_Nb&gt;&amp; __rhs) _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_do_xor(__rhs);
	return *this;
      }
      //@}

      //@{
      /**
       *  Operations on bitsets.
       *  @param  __position  The number of places to shift.
       *
       *  These should be self-explanatory.
       */
      bitset&lt;_Nb&gt;&amp;
      operator&lt;&lt;=(size_t __position) _GLIBCXX_NOEXCEPT
      {
	if (__builtin_expect(__position &lt; _Nb, 1))
	  {
	    this-&gt;_M_do_left_shift(__position);
	    this-&gt;_M_do_sanitize();
	  }
	else
	  this-&gt;_M_do_reset();
	return *this;
      }

      bitset&lt;_Nb&gt;&amp;
      operator&gt;&gt;=(size_t __position) _GLIBCXX_NOEXCEPT
      {
	if (__builtin_expect(__position &lt; _Nb, 1))
	  {
	    this-&gt;_M_do_right_shift(__position);
	    this-&gt;_M_do_sanitize();
	  }
	else
	  this-&gt;_M_do_reset();
	return *this;
      }
      //@}

      //@{
      /**
       *  These versions of single-bit set, reset, flip, and test are
       *  extensions from the SGI version.  They do no range checking.
       *  @ingroup SGIextensions
       */
      bitset&lt;_Nb&gt;&amp;
      _Unchecked_set(size_t __pos) _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_getword(__pos) |= _Base::_S_maskbit(__pos);
	return *this;
      }

      bitset&lt;_Nb&gt;&amp;
      _Unchecked_set(size_t __pos, int __val) _GLIBCXX_NOEXCEPT
      {
	if (__val)
	  this-&gt;_M_getword(__pos) |= _Base::_S_maskbit(__pos);
	else
	  this-&gt;_M_getword(__pos) &amp;= ~_Base::_S_maskbit(__pos);
	return *this;
      }

      bitset&lt;_Nb&gt;&amp;
      _Unchecked_reset(size_t __pos) _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_getword(__pos) &amp;= ~_Base::_S_maskbit(__pos);
	return *this;
      }

      bitset&lt;_Nb&gt;&amp;
      _Unchecked_flip(size_t __pos) _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_getword(__pos) ^= _Base::_S_maskbit(__pos);
	return *this;
      }

      _GLIBCXX_CONSTEXPR bool
      _Unchecked_test(size_t __pos) const _GLIBCXX_NOEXCEPT
      { return ((this-&gt;_M_getword(__pos) &amp; _Base::_S_maskbit(__pos))
		!= static_cast&lt;_WordT&gt;(0)); }
      //@}

      // Set, reset, and flip.
      /**
       *  @brief Sets every bit to true.
       */
      bitset&lt;_Nb&gt;&amp;
      set() _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_do_set();
	this-&gt;_M_do_sanitize();
	return *this;
      }

      /**
       *  @brief Sets a given bit to a particular value.
       *  @param  __position  The index of the bit.
       *  @param  __val  Either true or false, defaults to true.
       *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
       */
      bitset&lt;_Nb&gt;&amp;
      set(size_t __position, bool __val = true)
      {
	this-&gt;_M_check(__position, __N(&quot;bitset::set&quot;));
	return _Unchecked_set(__position, __val);
      }

      /**
       *  @brief Sets every bit to false.
       */
      bitset&lt;_Nb&gt;&amp;
      reset() _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_do_reset();
	return *this;
      }

      /**
       *  @brief Sets a given bit to false.
       *  @param  __position  The index of the bit.
       *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
       *
       *  Same as writing @c set(pos,false).
       */
      bitset&lt;_Nb&gt;&amp;
      reset(size_t __position)
      {
	this-&gt;_M_check(__position, __N(&quot;bitset::reset&quot;));
	return _Unchecked_reset(__position);
      }

      /**
       *  @brief Toggles every bit to its opposite value.
       */
      bitset&lt;_Nb&gt;&amp;
      flip() _GLIBCXX_NOEXCEPT
      {
	this-&gt;_M_do_flip();
	this-&gt;_M_do_sanitize();
	return *this;
      }

      /**
       *  @brief Toggles a given bit to its opposite value.
       *  @param  __position  The index of the bit.
       *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
       */
      bitset&lt;_Nb&gt;&amp;
      flip(size_t __position)
      {
	this-&gt;_M_check(__position, __N(&quot;bitset::flip&quot;));
	return _Unchecked_flip(__position);
      }

      /// See the no-argument flip().
      bitset&lt;_Nb&gt;
      operator~() const _GLIBCXX_NOEXCEPT
      { return bitset&lt;_Nb&gt;(*this).flip(); }

      //@{
      /**
       *  @brief  Array-indexing support.
       *  @param  __position  Index into the %bitset.
       *  @return A bool for a &lt;em&gt;const %bitset&lt;/em&gt;.  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
       */
      reference
      operator[](size_t __position)
      { return reference(*this, __position); }

      _GLIBCXX_CONSTEXPR bool
      operator[](size_t __position) const
      { return _Unchecked_test(__position); }
      //@}

      /**
       *  @brief Returns a numerical interpretation of the %bitset.
       *  @return  The integral equivalent of the bits.
       *  @throw  std::overflow_error  If there are too many bits to be
       *                               represented in an @c unsigned @c long.
       */
      unsigned long
      to_ulong() const
      { return this-&gt;_M_do_to_ulong(); }

#if __cplusplus &gt;= 201103L
      unsigned long long
      to_ullong() const
      { return this-&gt;_M_do_to_ullong(); }
#endif

      /**
       *  @brief Returns a character interpretation of the %bitset.
       *  @return  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&lt;class _CharT, class _Traits, class _Alloc&gt;
	std::basic_string&lt;_CharT, _Traits, _Alloc&gt;
	to_string() const
	{
	  std::basic_string&lt;_CharT, _Traits, _Alloc&gt; __result;
	  _M_copy_to_string(__result, _CharT('0'), _CharT('1'));
	  return __result;
	}

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

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 434. bitset::to_string() hard to use.
      template&lt;class _CharT, class _Traits&gt;
	std::basic_string&lt;_CharT, _Traits, std::allocator&lt;_CharT&gt; &gt;
	to_string() const
	{ return to_string&lt;_CharT, _Traits, std::allocator&lt;_CharT&gt; &gt;(); }

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

      template&lt;class _CharT&gt;
	std::basic_string&lt;_CharT, std::char_traits&lt;_CharT&gt;,
	                  std::allocator&lt;_CharT&gt; &gt;
	to_string() const
	{
	  return to_string&lt;_CharT, std::char_traits&lt;_CharT&gt;,
	                   std::allocator&lt;_CharT&gt; &gt;();
	}

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

      std::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;
      to_string() const
      {
	return to_string&lt;char, std::char_traits&lt;char&gt;,
	                 std::allocator&lt;char&gt; &gt;();
      }

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

      // Helper functions for string operations.
      template&lt;class _CharT, class _Traits&gt;
        void
        _M_copy_from_ptr(const _CharT*, size_t, size_t, size_t,
			 _CharT, _CharT);

      template&lt;class _CharT, class _Traits, class _Alloc&gt;
	void
	_M_copy_from_string(const std::basic_string&lt;_CharT,
			    _Traits, _Alloc&gt;&amp; __s, size_t __pos, size_t __n,
			    _CharT __zero, _CharT __one)
	{ _M_copy_from_ptr&lt;_CharT, _Traits&gt;(__s.data(), __s.size(), __pos, __n,
					    __zero, __one); }

      template&lt;class _CharT, class _Traits, class _Alloc&gt;
	void
        _M_copy_to_string(std::basic_string&lt;_CharT, _Traits, _Alloc&gt;&amp;,
			  _CharT, _CharT) const;

      // NB: Backward compat.
      template&lt;class _CharT, class _Traits, class _Alloc&gt;
	void
	_M_copy_from_string(const std::basic_string&lt;_CharT,
			    _Traits, _Alloc&gt;&amp; __s, size_t __pos, size_t __n)
	{ _M_copy_from_string(__s, __pos, __n, _CharT('0'), _CharT('1')); }

      template&lt;class _CharT, class _Traits, class _Alloc&gt;
	void
        _M_copy_to_string(std::basic_string&lt;_CharT, _Traits,_Alloc&gt;&amp; __s) const
	{ _M_copy_to_string(__s, _CharT('0'), _CharT('1')); }

      /// Returns the number of bits which are set.
      size_t
      count() const _GLIBCXX_NOEXCEPT
      { return this-&gt;_M_do_count(); }

      /// Returns the total number of bits.
      _GLIBCXX_CONSTEXPR size_t
      size() const _GLIBCXX_NOEXCEPT
      { return _Nb; }

      //@{
      /// These comparisons for equality/inequality are, well, @e bitwise.
      bool
      operator==(const bitset&lt;_Nb&gt;&amp; __rhs) const _GLIBCXX_NOEXCEPT
      { return this-&gt;_M_is_equal(__rhs); }

      bool
      operator!=(const bitset&lt;_Nb&gt;&amp; __rhs) const _GLIBCXX_NOEXCEPT
      { return !this-&gt;_M_is_equal(__rhs); }
      //@}

      /**
       *  @brief Tests the value of a bit.
       *  @param  __position  The index of a bit.
       *  @return  The value at @a pos.
       *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
       */
      bool
      test(size_t __position) const
      {
	this-&gt;_M_check(__position, __N(&quot;bitset::test&quot;));
	return _Unchecked_test(__position);
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // DR 693. std::bitset::all() missing.
      /**
       *  @brief Tests whether all the bits are on.
       *  @return  True if all the bits are set.
       */
      bool
      all() const _GLIBCXX_NOEXCEPT
      { return this-&gt;template _M_are_all&lt;_Nb&gt;(); }

      /**
       *  @brief Tests whether any of the bits are on.
       *  @return  True if at least one bit is set.
       */
      bool
      any() const _GLIBCXX_NOEXCEPT
      { return this-&gt;_M_is_any(); }

      /**
       *  @brief Tests whether any of the bits are on.
       *  @return  True if none of the bits are set.
       */
      bool
      none() const _GLIBCXX_NOEXCEPT
      { return !this-&gt;_M_is_any(); }

      //@{
      /// Self-explanatory.
      bitset&lt;_Nb&gt;
      operator&lt;&lt;(size_t __position) const _GLIBCXX_NOEXCEPT
      { return bitset&lt;_Nb&gt;(*this) &lt;&lt;= __position; }

      bitset&lt;_Nb&gt;
      operator&gt;&gt;(size_t __position) const _GLIBCXX_NOEXCEPT
      { return bitset&lt;_Nb&gt;(*this) &gt;&gt;= __position; }
      //@}

      /**
       *  @brief  Finds the index of the first &quot;on&quot; bit.
       *  @return  The index of the first bit set, or size() if not found.
       *  @ingroup SGIextensions
       *  @sa  _Find_next
       */
      size_t
      _Find_first() const _GLIBCXX_NOEXCEPT
      { return this-&gt;_M_do_find_first(_Nb); }

      /**
       *  @brief  Finds the index of the next &quot;on&quot; bit after prev.
       *  @return  The index of the next bit set, or size() if not found.
       *  @param  __prev  Where to start searching.
       *  @ingroup SGIextensions
       *  @sa  _Find_first
       */
      size_t
      _Find_next(size_t __prev) const _GLIBCXX_NOEXCEPT
      { return this-&gt;_M_do_find_next(__prev, _Nb); }
    };

  // Definitions of non-inline member functions.
  template&lt;size_t _Nb&gt;
    template&lt;class _CharT, class _Traits&gt;
      void
      bitset&lt;_Nb&gt;::
      _M_copy_from_ptr(const _CharT* __s, size_t __len,
		       size_t __pos, size_t __n, _CharT __zero, _CharT __one)
      {
	reset();
	const size_t __nbits = std::min(_Nb, std::min(__n, size_t(__len - __pos)));
	for (size_t __i = __nbits; __i &gt; 0; --__i)
	  {
	    const _CharT __c = __s[__pos + __nbits - __i];
	    if (_Traits::eq(__c, __zero))
	      ;
	    else if (_Traits::eq(__c, __one))
	      _Unchecked_set(__i - 1);
	    else
	      __throw_invalid_argument(__N(&quot;bitset::_M_copy_from_ptr&quot;));
	  }
      }

  template&lt;size_t _Nb&gt;
    template&lt;class _CharT, class _Traits, class _Alloc&gt;
      void
      bitset&lt;_Nb&gt;::
      _M_copy_to_string(std::basic_string&lt;_CharT, _Traits, _Alloc&gt;&amp; __s,
			_CharT __zero, _CharT __one) const
      {
	__s.assign(_Nb, __zero);
	for (size_t __i = _Nb; __i &gt; 0; --__i)
	  if (_Unchecked_test(__i - 1))
	    _Traits::assign(__s[_Nb - __i], __one);
      }

  // 23.3.5.3 bitset operations:
  //@{
  /**
   *  @brief  Global bitwise operations on bitsets.
   *  @param  __x  A bitset.
   *  @param  __y  A bitset of the same size as @a __x.
   *  @return  A new bitset.
   *
   *  These should be self-explanatory.
  */
  template&lt;size_t _Nb&gt;
    inline bitset&lt;_Nb&gt;
    operator&amp;(const bitset&lt;_Nb&gt;&amp; __x, const bitset&lt;_Nb&gt;&amp; __y) _GLIBCXX_NOEXCEPT
    {
      bitset&lt;_Nb&gt; __result(__x);
      __result &amp;= __y;
      return __result;
    }

  template&lt;size_t _Nb&gt;
    inline bitset&lt;_Nb&gt;
    operator|(const bitset&lt;_Nb&gt;&amp; __x, const bitset&lt;_Nb&gt;&amp; __y) _GLIBCXX_NOEXCEPT
    {
      bitset&lt;_Nb&gt; __result(__x);
      __result |= __y;
      return __result;
    }

  template &lt;size_t _Nb&gt;
    inline bitset&lt;_Nb&gt;
    operator^(const bitset&lt;_Nb&gt;&amp; __x, const bitset&lt;_Nb&gt;&amp; __y) _GLIBCXX_NOEXCEPT
    {
      bitset&lt;_Nb&gt; __result(__x);
      __result ^= __y;
      return __result;
    }
  //@}

  //@{
  /**
   *  @brief Global I/O operators for bitsets.
   *
   *  Direct I/O between streams and bitsets is supported.  Output is
   *  straightforward.  Input will skip whitespace, only accept @a 0 and @a 1
   *  characters, and will only extract as many digits as the %bitset will
   *  hold.
  */
  template&lt;class _CharT, class _Traits, size_t _Nb&gt;
    std::basic_istream&lt;_CharT, _Traits&gt;&amp;
    operator&gt;&gt;(std::basic_istream&lt;_CharT, _Traits&gt;&amp; __is, bitset&lt;_Nb&gt;&amp; __x)
    {
      typedef typename _Traits::char_type          char_type;
      typedef std::basic_istream&lt;_CharT, _Traits&gt;  __istream_type;
      typedef typename __istream_type::ios_base    __ios_base;

      std::basic_string&lt;_CharT, _Traits&gt; __tmp;
      __tmp.reserve(_Nb);

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 303. Bitset input operator underspecified
      const char_type __zero = __is.widen('0');
      const char_type __one = __is.widen('1');

      typename __ios_base::iostate __state = __ios_base::goodbit;
      typename __istream_type::sentry __sentry(__is);
      if (__sentry)
	{
	  __try
	    {
	      for (size_t __i = _Nb; __i &gt; 0; --__i)
		{
		  static typename _Traits::int_type __eof = _Traits::eof();

		  typename _Traits::int_type __c1 = __is.rdbuf()-&gt;sbumpc();
		  if (_Traits::eq_int_type(__c1, __eof))
		    {
		      __state |= __ios_base::eofbit;
		      break;
		    }
		  else
		    {
		      const char_type __c2 = _Traits::to_char_type(__c1);
		      if (_Traits::eq(__c2, __zero))
			__tmp.push_back(__zero);
		      else if (_Traits::eq(__c2, __one))
			__tmp.push_back(__one);
		      else if (_Traits::
			       eq_int_type(__is.rdbuf()-&gt;sputbackc(__c2),
					   __eof))
			{
			  __state |= __ios_base::failbit;
			  break;
			}
		    }
		}
	    }
	  __catch(__cxxabiv1::__forced_unwind&amp;)
	    {
	      __is._M_setstate(__ios_base::badbit);
	      __throw_exception_again;
	    }
	  __catch(...)
	    { __is._M_setstate(__ios_base::badbit); }
	}

      if (__tmp.empty() &amp;&amp; _Nb)
	__state |= __ios_base::failbit;
      else
	__x._M_copy_from_string(__tmp, static_cast&lt;size_t&gt;(0), _Nb,
				__zero, __one);
      if (__state)
	__is.setstate(__state);
      return __is;
    }

  template &lt;class _CharT, class _Traits, size_t _Nb&gt;
    std::basic_ostream&lt;_CharT, _Traits&gt;&amp;
    operator&lt;&lt;(std::basic_ostream&lt;_CharT, _Traits&gt;&amp; __os,
	       const bitset&lt;_Nb&gt;&amp; __x)
    {
      std::basic_string&lt;_CharT, _Traits&gt; __tmp;

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 396. what are characters zero and one.
      const ctype&lt;_CharT&gt;&amp; __ct = use_facet&lt;ctype&lt;_CharT&gt; &gt;(__os.getloc());
      __x._M_copy_to_string(__tmp, __ct.widen('0'), __ct.widen('1'));
      return __os &lt;&lt; __tmp;
    }
  //@}

_GLIBCXX_END_NAMESPACE_CONTAINER
} // namespace std

#undef _GLIBCXX_BITSET_WORDS
#undef _GLIBCXX_BITSET_BITS_PER_WORD
#undef _GLIBCXX_BITSET_BITS_PER_ULL

#if __cplusplus &gt;= 201103L

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  // DR 1182.
  /// std::hash specialization for bitset.
  template&lt;size_t _Nb&gt;
    struct hash&lt;_GLIBCXX_STD_C::bitset&lt;_Nb&gt;&gt;
    : public __hash_base&lt;size_t, _GLIBCXX_STD_C::bitset&lt;_Nb&gt;&gt;
    {
      size_t
      operator()(const _GLIBCXX_STD_C::bitset&lt;_Nb&gt;&amp; __b) const noexcept
      {
	const size_t __clength = (_Nb + __CHAR_BIT__ - 1) / __CHAR_BIT__;
	return std::_Hash_impl::hash(__b._M_getdata(), __clength);
      }
    };

  template&lt;&gt;
    struct hash&lt;_GLIBCXX_STD_C::bitset&lt;0&gt;&gt;
    : public __hash_base&lt;size_t, _GLIBCXX_STD_C::bitset&lt;0&gt;&gt;
    {
      size_t
      operator()(const _GLIBCXX_STD_C::bitset&lt;0&gt;&amp;) const noexcept
      { return 0; }
    };

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif // C++11

#ifdef _GLIBCXX_DEBUG
# include &lt;debug/bitset&gt;
#endif

#ifdef _GLIBCXX_PROFILE
# include &lt;profile/bitset&gt;
#endif

#endif /* _GLIBCXX_BITSET */
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