What's the correct result of boost::lexical_cast and std::to_string for unsigned char

Question

What's the correct result of below cast from char to string?

I heard that old boost version 1.46 lexical_cast output was 56, I don't have that version near me that I can't test it. But boost library(1.49) output is: 8

  unsigned char c= 56;
  std::string s = boost::lexical_cast<std::string>(c);
  std::cout << "boost::lexical_cast: " << s << std::endl;

C++11 to_string output is: 56

  std::cout << "std::to_string: " << std::to_string(c) << std::endl;

Answer 1

Both are correct. to_string does not care that c is of type char, it will read the number in it and cast it into string.

On the other hand, lexical_cast<std::string> seems to interpret variables of type char as an ascii value. 56 is the ascii value of 8.

Answer 2

std::to_string only provides overloads for numeric types, probably resolving to the unsigned version in this case. lexical_cast, OTOH, relies on std::ostream::operator<< to perform the conversion, thus treating c as a character.