Converting integer to Roman Numeral

Question

I have a test due in about four hours and one of the questions asks us to convert a user-inputed integer up to 100 into a roman numeral. I think my code is very close (I fou

Answer 1

Function to Convert Decimal to Roman Numrals string toLongRoman(int x) {

string Romanvalue;

string  Roman[13] = { "M","CM","D","CD", "C","XC", "L","XL", "X","IX","V","IV", "I" };
int Numbers[13] = { 1000, 900, 500,400, 100,90,50,40,10,9,5,4,1 };

for (int index = 0; index < 13; index++) {



        while (x >= Numbers[index]) {
            Romanvalue += Roman[index];


            x -= Numbers[index];

        }
    }

    return Romanvalue;

Answer 2

Joachim found the first problem, this code is always executed and overwrite input with 100.

    if(input = 100)
    {
        romnum + 'C';

    }

Now, why don't you see anything? That's because you miss another =. All other code correctly uses += but this uses +. As a result, this doesn't assign the resulting string back to romnum.

BTW, since romnum is still empty, you can use romnum = 'C' or romnum += 'C' interchangeably.

Answer 3

From http://rosettacode.org/wiki/Roman_numerals/Encode#C.2B.2B

std::string to_roman(unsigned int value)
{
    struct romandata_t { unsigned int value; char const* numeral; };
    const struct romandata_t romandata[] =
    {
        {1000, "M"}, {900, "CM"},
        {500, "D"}, {400, "CD"},
        {100, "C"}, { 90, "XC"},
        { 50, "L"}, { 40, "XL"},
        { 10, "X"}, { 9, "IX"},
        { 5, "V"}, { 4, "IV"},
        { 1, "I"},
        { 0, NULL} // end marker
    };

    std::string result;
    for (const romandata_t* current = romandata; current->value > 0; ++current)
    {
        while (value >= current->value)
        {
            result += current->numeral;
            value -= current->value;
        }
    }
    return result;
}