bitset Class Template Reference
[Containers]

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

Inherits std::_Base_bitset< _GLIBCXX_BITSET_WORDS(_Nb)>.

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Detailed Description

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

(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++/ext/sgiexts.html#ch23 for a description of extensions.

Definition at line 645 of file bitset.


Constructor & Destructor Documentation

bitset (  )  [inline]

All bits set to zero.

Definition at line 735 of file bitset.

bitset ( unsigned long  __val  )  [inline]

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

Definition at line 739 of file bitset.

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 754 of file bitset.

References basic_string::size().

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 775 of file bitset.

References basic_string::size().


Member Function Documentation

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 880 of file bitset.

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 873 of file bitset.

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 863 of file bitset.

bool _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 887 of file bitset.

bool any (  )  const [inline]

Tests whether any of the bits are on.

Returns:
True if at least one bit is set.

Definition at line 1099 of file bitset.

size_t count (  )  const [inline]

Returns the number of bits which are set.

Definition at line 1061 of file bitset.

References std::count().

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 960 of file bitset.

bitset<_Nb>& flip (  )  [inline]

Toggles every bit to its opposite value.

Definition at line 947 of file bitset.

bool none (  )  const [inline]

Tests whether any of the bits are on.

Returns:
True if none of the bits are set.

Definition at line 1107 of file bitset.

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

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

Definition at line 1076 of file bitset.

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 794 of file bitset.

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

Self-explanatory.

Definition at line 1113 of file bitset.

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 823 of file bitset.

bool operator== ( const bitset< _Nb > &  __rhs  )  const [inline]

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

Definition at line 1072 of file bitset.

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

Self-explanatory.

Definition at line 1117 of file bitset.

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 836 of file bitset.

bool 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.

Definition at line 994 of file bitset.

reference 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.

Definition at line 990 of file bitset.

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 808 of file bitset.

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 801 of file bitset.

bitset<_Nb> operator~ (  )  const [inline]

See the no-argument flip().

Definition at line 969 of file bitset.

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 936 of file bitset.

bitset<_Nb>& reset (  )  [inline]

Sets every bit to false.

Definition at line 922 of file bitset.

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 911 of file bitset.

bitset<_Nb>& set (  )  [inline]

Sets every bit to true.

Definition at line 897 of file bitset.

size_t size (  )  const [inline]

Returns the total number of bits.

Definition at line 1066 of file bitset.

bool 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 1087 of file bitset.

std::basic_string<_CharT, _Traits, _Alloc> to_string (  )  const [inline]

Retuns 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 1018 of file bitset.

unsigned long to_ulong (  )  const [inline]

Retuns 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 1005 of file bitset.


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

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