To construct an std::bitset object, use one of the available constructors:

• An empty bitset with all bits set to 0:

        std::bitset<8> b1; // [0,0,0,0,0,0,0,0]

• A bitset from a numerical value:

        std::bitset<8> b2{ 10 }; // [0,0,0,0,1,0,1,0]

• A bitset from a string of '0' and '1':

        std::bitset<8> b3{ "1010"s }; // [0,0,0,0,1,0,1,0]

• A bitset from a string containing any two characters representing '0' and '1'; in this case, we must specify which character represents a 0 and which character represents a 1:

        std::bitset<8> b4 
          { "ooooxoxo"s, 0, std::string::npos, 'o', 'x' }; 
          // [0,0,0,0,1,0,1,0]

To test individual bits in the set or the entire set for specific values, use any of the available methods:

• count() to get the number of bits set to 1:

        std::bitset<8> bs{ 10 };
        std::cout << "has " << bs.count() << " 1s" << std::endl;

• any() to check whether there is at least one bit set to 1:

        if (bs.any()) std::cout << "has some 1s" << std::endl;

• all() to check whether all the bits are set to 1:

        if (bs.all()) std::cout << "has only 1s" << std::endl;

• none() to check whether all the bits are set to 0:

        if (bs.none()) std::cout << "has no 1s" << std::endl;

• test() to check the value of an individual bit:

        if (!bs.test(0)) std::cout << "even" << std::endl;

• operator[] to access and test individual bits:

        if(!bs[0]) std::cout << "even" << std::endl;

To modify the content of a bitset, use any of the following methods:

• Member operators |=, &=, ^= , and ~ to perform binary or, and, xor, and not operations, or non-member operators |, &, and ^:

        std::bitset<8> b1{ 42 }; // [0,0,1,0,1,0,1,0]
        std::bitset<8> b2{ 11 }; // [0,0,0,0,1,0,1,1]
        auto b3 = b1 | b2;       // [0,0,1,0,1,0,1,1]
        auto b4 = b1 & b2;       // [0,0,0,0,1,0,1,0]
        auto b5 = b1 ^ b2;       // [1,1,0,1,1,1,1,0]
        auto b6 = ~b1;           // [1,1,0,1,0,1,0,1]

• Member operators <<=, <<, >>=, >> to perform shifting operations:

        auto b7 = b1 << 2;       // [1,0,1,0,1,0,0,0]
        auto b8 = b1 >> 2;       // [0,0,0,0,1,0,1,0]

• flip() to toggle the entire set or an individual bit from 0 to 1 or from 1 to 0:

        b1.flip();               // [1,1,0,1,0,1,0,1]
        b1.flip(0);              // [1,1,0,1,0,1,0,0]

• set() to change the entire set or an individual bit to true or the specified value:

        b1.set(0, true);         // [1,1,0,1,0,1,0,1]
        b1.set(0, false);        // [1,1,0,1,0,1,0,0]

• reset() to change the entire set or an individual bit to false:

        b1.reset(2);             // [1,1,0,1,0,0,0,0]

To convert a bitset to a numerical or string value, use the following methods:

• to_ulong() and to_ullong() to convert to unsigned long or unsigned long long:

        std::bitset<8> bs{ 42 };
        auto n1 = bs.to_ulong();  // n1 = 42UL
        auto n2 = bs.to_ullong(); // n2 = 42ULL

• to_string() to convert to std::basic_string; by default the result is a string containing '0' and '1', but you can specify a different character for these two values:

        auto s1 = bs.to_string();         // s1 = "00101010"
        auto s2 = bs.to_string('o', 'x'), // s2 = "ooxoxoxo"