libstdc++
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The bitset class represents a fixed-size sequence of bits. More...
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.
std::bitset< _Nb >::bitset | ( | ) | [inline] |
std::bitset< _Nb >::bitset | ( | unsigned long | __val | ) | [inline] |
std::bitset< _Nb >::bitset | ( | const std::basic_string< _CharT, _Traits, _Alloc > & | __s, |
size_t | __position = 0 |
||
) | [inline, explicit] |
Use a subset of a string.
s | A string of '0' and '1' characters. |
position | Index of the first character in s to use; defaults to zero. |
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'. |
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.
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. |
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'. |
bool std::bitset< _Nb >::all | ( | ) | const [inline] |
bool std::bitset< _Nb >::any | ( | ) | const [inline] |
size_t std::bitset< _Nb >::count | ( | ) | const [inline] |
bitset<_Nb>& std::bitset< _Nb >::flip | ( | size_t | __position | ) | [inline] |
Toggles a given bit to its opposite value.
position | The index of the bit. |
std::out_of_range | If pos is bigger the size of the set. |
bitset<_Nb>& std::bitset< _Nb >::flip | ( | ) | [inline] |
Toggles every bit to its opposite value.
Definition at line 963 of file bitset.
Referenced by std::bitset< _S_match_flag_last >::operator~().
bool std::bitset< _Nb >::none | ( | ) | const [inline] |
bool std::bitset< _Nb >::operator!= | ( | const bitset< _Nb > & | __rhs | ) | const [inline] |
bitset<_Nb>& std::bitset< _Nb >::operator&= | ( | const bitset< _Nb > & | __rhs | ) | [inline] |
bitset<_Nb> std::bitset< _Nb >::operator<< | ( | size_t | __position | ) | const [inline] |
bitset<_Nb>& std::bitset< _Nb >::operator<<= | ( | size_t | __position | ) | [inline] |
bool std::bitset< _Nb >::operator== | ( | const bitset< _Nb > & | __rhs | ) | const [inline] |
bitset<_Nb> std::bitset< _Nb >::operator>> | ( | size_t | __position | ) | const [inline] |
bitset<_Nb>& std::bitset< _Nb >::operator>>= | ( | size_t | __position | ) | [inline] |
bool std::bitset< _Nb >::operator[] | ( | size_t | __position | ) | const [inline] |
Array-indexing support.
position | Index into the bitset. |
_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 std::bitset< _Nb >::operator[] | ( | size_t | __position | ) | [inline] |
Array-indexing support.
position | Index into the bitset. |
_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
bitset<_Nb>& std::bitset< _Nb >::operator^= | ( | const bitset< _Nb > & | __rhs | ) | [inline] |
bitset<_Nb>& std::bitset< _Nb >::operator|= | ( | const bitset< _Nb > & | __rhs | ) | [inline] |
bitset<_Nb> std::bitset< _Nb >::operator~ | ( | ) | const [inline] |
bitset<_Nb>& std::bitset< _Nb >::reset | ( | ) | [inline] |
bitset<_Nb>& std::bitset< _Nb >::reset | ( | size_t | __position | ) | [inline] |
Sets a given bit to false.
position | The index of the bit. |
std::out_of_range | If pos is bigger the size of the set. |
Same as writing set(pos,false)
.
bitset<_Nb>& std::bitset< _Nb >::set | ( | ) | [inline] |
bitset<_Nb>& std::bitset< _Nb >::set | ( | size_t | __position, |
bool | __val = true |
||
) | [inline] |
Sets a given bit to a particular value.
position | The index of the bit. |
val | Either true or false, defaults to true. |
std::out_of_range | If pos is bigger the size of the set. |
size_t std::bitset< _Nb >::size | ( | ) | const [inline] |
bool std::bitset< _Nb >::test | ( | size_t | __position | ) | const [inline] |
Tests the value of a bit.
position | The index of a bit. |
std::out_of_range | If pos is bigger the size of the set. |
std::basic_string<_CharT, _Traits, _Alloc> std::bitset< _Nb >::to_string | ( | ) | const [inline] |
unsigned long std::bitset< _Nb >::to_ulong | ( | ) | const [inline] |
Returns a numerical interpretation of the bitset.
std::overflow_error | If there are too many bits to be represented in an unsigned long . |