How can I convert hexadecimal numbers to binary in C++?

Question

I am taking a beginning C++ class, and would like to convert letters between hex representations and binary. I can manage to print out the hex numbers using:

Answer 1

You can easily write a mapping between the hex charachters an their binary 'nibbles':

std::string HexCharToNibble( char c ) {
switch (c) {
  case '0': return "0000";
  case '1': return "0001";
  //... fill in the rest
  case 'f': return "1111";
  default: assert(false); return "bad input";
};