std::bitset<N>::bitset

 

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std::bitset

Member types

bitset::reference

Member functions

bitset::bitset

bitset::operator==bitset::operator!= (until C++20)

Element access

bitset::operator[]

bitset::test

bitset::allbitset::anybitset::none (C++11)

bitset::count

Capacity

bitset::size

Modifiers

bitset::operator&=bitset::operator|=bitset::operator^=bitset::operator~

bitset::operator<<=bitset::operator>>=bitset::operator<<bitset::operator>>

bitset::set

bitset::reset

bitset::flip

Conversions

bitset::to_string

bitset::to_ulong

bitset::to_ullong (C++11)

Non-member functions

operator&operator|operator^

operator<<operator>>

Helper classes

std::hash (C++11)

 

	(1)
bitset();			(until C++11)
constexpr bitset() noexcept;			(since C++11)
		(2)
bitset( unsigned long val );				(until C++11)
constexpr bitset( unsigned long long val ) noexcept;				(since C++11)
			(3)
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 = std::basic_string<CharT,Traits,Alloc>::npos );					(until C++11)
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 = std::basic_string<CharT,Traits,Alloc>::npos,                  CharT zero = CharT('0'),                  CharT one = CharT('1') );					(since C++11) (constexpr since C++23)
template< class 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') );				(4)	(since C++11) (constexpr since C++23)

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, initializing the first (rightmost, least significant) M bit positions to the corresponding bit values of val, where M is the smaller of the number of bits in an unsigned long long and the number of bits N in the bitset being constructed. If M is less than N (the bitset is longer than 32 (until C++11)64 (since C++11) bits, for typical implementations of unsigned long (since C++11)long), the remaining bit positions are initialized to zeroes.

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. Traits::eq() is used to compare the character values.

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. Equivalent to

bitset(n == basic_string<CharT>::npos 
          ? basic_string<CharT>(str)
          : basic_string<CharT>(str, n), 0, n, zero, one)

Parameters

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

Exceptions

3) std::out_of_range if pos > str.size(), std::invalid_argument if any character is not one or zero

4) std::invalid_argument if any character is not one or zero

Example

Run this code

#include <bitset>
#include <string>
#include <iostream>
#include <climits>
 
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]
    std::bitset<70> bl(ULLONG_MAX); // [0,0,0,0,0,0,1,1,1,...,1,1,1] in C++11
    std::bitset<8> bs(0xfff0);      // [1,1,1,1,0,0,0,0]
 
    // 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]
 
    std::cout <<   "b1: " << b1 << "\nb2: " << b2 << "\nbl: " << bl
              << "\nbs: " << bs << "\nb3: " << b3 << "\nb4: " << b4
              << "\nb5: " << b5 << "\nb6: " << b6 << "\nb7: " << b7 << '\n';
}

Possible output:

b1: 00000000
b2: 00101010
bl: 0000001111111111111111111111111111111111111111111111111111111111111111
bs: 11110000
b3: 00110010
b4: 00000010
b5: 00000001
b6: 01001101
b7: 00001111

See also

set	sets bits to true or given value (public member function)
reset	sets bits to false (public member function)