Question

How do you convert back a binary to string?

std::string test1("Hello");
std::bitset<8> test2;
test2 = std::bitset<8>(test1.c_str()[0]);

std::cout << test2 << std::endl;
std::string test3=test2.to_string<char,std::char_traits<char>,std::allocator<char> >(); 
std::cout << test3 << std::endl;

This will output:
01001000
01001000

How do i output back “Hello”?

Answer 1

Your std::bitset<8> clearly can’t hold the world "Hello". After all, you are only representing 8 bits. What you can do is to convert each char to a std::bitset<8> (assuming char is 8 bit, of course, which is typically the case but not guaranteed) and the std::bitset<8> back to its value as an integer using to_ulong(). Converting this value thus obtained to char should yield the original character:

std::bitset<8> c(test1[0]);
std::cout << "c=" << c << " char(c.to_ulong())=" << char(c.to_ulong()) << "\n";

To get "Hello" back you’d need a bigger std::bitset<N> and you’d need to make sure you extract the correct bits to reassemble the correct individual character.