Can I set this string as the value of a bitset<256> really quickly?
Yes, you can just use the constructor, the example below is taken right from the document and works for 256
as well:
std::string bit_string = "110010";
std::bitset<8> b3(bit_string); // [0,0,1,1,0,0,1,0]
std::cout << b3.to_string() << std::endl ;