< cpp‎ | utility‎ | bitset
Revision as of 16:53, 1 July 2013 by P12bot (Talk | contribs)

constexpr bitset() noexcept;
constexpr bitset( unsigned long long val ) noexcept;
template< class CharT, class Traits, class 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 =

(until C++11)
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 =
        CharT zero = CharT(0),

        CharT one = CharT(1));
(since C++11)
template< class CharT >

explicit bitset( const CharT* str,
                 typename std::basic_string<CharT>::size_type n =
                 CharT zero = CharT(0),

                 CharT one = CharT(1));
(4) (since C++11)

Constructs a new bitset from one of several optional data sources:

1) Default constructor. Constructs a bitset with all bits set to zero.
2) Constructs a bitset using the bits in val. If the N is the size of the bitset and M is the number of set bits in val, then only min(N, M) bits will be included in the bitset.
3) Constructs a bitset using the characters in the std::basic_string str. An optional starting position pos and length n can be provided, as well as characters denoting alternate values for set (one) and unset (zero) bits.
The effective length of the initializing string is min(n, str.size() - pos).
If pos > str.size(), this constructor throws std::out_of_range. If any characters examined in str are not zero or one, it throws std::invalid_argument.
4) Similar to (3), but uses a CharT* instead of a std::basic_string.



val - number used to initialize the bitset
str - string used to initialize the bitset
pos - a starting offset into str
n - number of characters to use from str
one - alternate character for set bits in str
zero - alternate character for unset bits in str


1. none

2. none

3. std::out_of_range if pos > str.size()

4. none


#include <bitset>
#include <string>
int main() 
    // empty constructor
    std::bitset<8> b1; // [0,0,0,0,0,0,0,0]
    // unsigned long long constructor
    std::bitset<8> b2(42); // [0,0,1,0,1,0,1,0]
    // string constructor
    std::string bit_string = "110010";
    std::bitset<8> b3(bit_string);       // [0,0,1,1,0,0,1,0]
    std::bitset<8> b4(bit_string, 2);    // [0,0,0,0,0,0,1,0]
    std::bitset<8> b5(bit_string, 2, 3); // [0,0,0,0,0,0,0,1]
    // string constructor using custom zero/one digits
    std::string alpha_bit_string = "aBaaBBaB";
    std::bitset<8> b6(alpha_bit_string, 0, alpha_bit_string.size(),
                      'a', 'B');         // [0,1,0,0,1,1,0,1]
    // char* constructor using custom digits
    std::bitset<8> b7("XXXXYYYY", 8, 'X', 'Y'); // [0,0,0,0,1,1,1,1]
    return 0;

See also

sets bits to true or given value
(public member function) [edit]
sets bits to false
(public member function) [edit]