#include <cstring>
#include <cassert>

//From http://www.richelbilderbeek.nl/CppHexStrIsInt.htm
//This solution was inspired by AsmGuru62
//http://www.programmersheaven.com/c/authorpage.asp?AuthorID=12069
//Checks if a C-style string only contains hexadecimal characters
bool IsAllHex (const char* const must_be_hex)
{
  char copy_of_param[64];

  return(
    std::strtok (
      std::strcpy(copy_of_param, must_be_hex),
      "0123456789ABCDEFabcdef") == 0);
}

int main()
{
  assert(IsAllHex("0")==true);
  assert(IsAllHex("9")==true);
  assert(IsAllHex("A")==true);
  assert(IsAllHex("F")==true);
  assert(IsAllHex("-F")==false); //Does not accept negatives
  assert(IsAllHex("-F85AE")==false); //Does not accept negatives
  assert(IsAllHex("FFFFFFFFFFFFFFFFFFFFFFFFFFF")==true);
  assert(IsAllHex("G")==false);
}


//As option #1 also has defects in detecting negatives, you might want to change
//the IsAllHex to the one below:


//From http://www.richelbilderbeek.nl/CppHexStrIsInt.htm
//This solution was inspired by AsmGuru62
//http://www.programmersheaven.com/c/authorpage.asp?AuthorID=12069
//Checks if a C-style string only contains hexadecimal characters
//and minuses
bool IsAllHex (const char* const must_be_hex)
{
  char copy_of_param[64];

  return(
    std::strtok (
      std::strcpy(copy_of_param, must_be_hex),
      "0123456789ABCDEFabcdef-") == 0);
}