std::bitset::bitset(3)

NAME
std::bitset::bitset - std::bitset::bitset

Synopsis
   bitset(); (until
                        C++11)
   constexpr bitset() noexcept; (since
                        C++11)
   bitset( unsigned long val ); (until
                        C++11)
   constexpr bitset( unsigned long long val ) (since
   noexcept; C++11)
   template< class CharT, class Traits, class Alloc
   >
   explicit bitset( const
   std::basic_string<CharT,Traits,Alloc>& str,
   typename (until
   std::basic_string<CharT,Traits,Alloc>::size_type C++11)
   pos = 0,
   typename
   std::basic_string<CharT,Traits,Alloc>::size_type
   n = std::basic_string<CharT,Traits,Alloc>::npos
   );
   template< class CharT, class Traits, class Alloc (1)
   >
                        (2)
   explicit bitset( const
   std::basic_string<CharT,Traits,Alloc>& str, (3) (since
   typename C++11)
   std::basic_string<CharT,Traits,Alloc>::size_type (constexpr
   pos = 0, since
   typename C++23)
   std::basic_string<CharT,Traits,Alloc>::size_type
   n = std::basic_string<CharT,Traits,Alloc>::npos,
   CharT zero = CharT('0'),
   CharT one = CharT('1') );
   template< class CharT >
                        (since
   explicit bitset( const CharT* str, C++11)
   typename std::basic_string<CharT>::size_type (4) (constexpr
   n = std::basic_string<CharT>::npos, since
   CharT zero = CharT('0'), C++23)
   CharT one = CharT('1') );
   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)