#ifdef TEST_PROGRAM
  #include <iostream>
  #include <cstdlib>
#endif // TEST_PROGRAM

#include <string>

static const char rc[] = { 'I', 'V', 'X', 'L', 'C', 'D', 'M' };
static const int rMin(1), rMax(3999);

std::string roman(
  int dec
) {
  static const size_t bufSize = 24;

  // Returns a std::string containing the representation, in Roman
  // numerals, of the decimal number "dec".  "rMin" and "rMax" define
  // the range we can represent with the numerals defined in "rc".

  if (dec < rMin   ||   dec > rMax) return "Out of range";

  char         buf[bufSize];
  const char * pc               = rc;
  char *       last             = buf + bufSize;

  *--last = '\0';

  do {
    if (int digit = dec % 10) {

      int ni = digit % 5;
      if (ni == 4) {
        if (digit == 4) *--last = *(pc+1);
        else            *--last = *(pc+2);
        *--last = *pc;

      } else {
        switch (ni) {
          case 0:
            *--last = *(pc+1);
            break;
          case 1:  case 2:  case 3:
            while (ni--) *--last = *pc;
            if (digit > 4) *--last = *(pc+1);
            break;
        }
      }
    }

    dec /= 10;
    pc  += 2;
  } while (dec);

  return last;
}

#ifdef TEST_PROGRAM
int main(
  int    argc,
  char * argv[]
) {
  if (argc == 1) {
    std::cerr << "Usage:\t" << argv[0] << " i1 [ ,i2 [ ,i3 [ "
              << "... ]]]\n\n\tConverts the command line "
              << "arguments (numbers in the range " << rMin
              << "..." << rMax << ")\n\tto Roman numerals.\n";
  } else {
    while (--argc) {
      int i = std::atoi(*++argv);
      std::cout << i << "\t==> " << roman(i) << std::endl;
    }
  }
}
#endif // TEST_PROGRAM