Conversor de Numeros Arabicos a Romanos

#include <iostream>
///Nota solo comvierte de 1 a 3999.
int main () {

    std::cout << "Ingrese digito: ";
    int cont = 0, numero;
    std::cin >> numero;
    int unidades, decenas, centenas, miles;
    while (numero != 0) {
        if (cont == 0) {
            unidades = numero % 10;
        } else if (cont == 1) {
            decenas = numero % 10;
        } else if (cont == 2) {
            centenas = numero % 10;
        } else if (cont > 2) {
            miles = numero % 10;
        }
        numero = numero / 10;
        ++cont;
    }


    int aux = miles;
    while (aux != 0 && miles < 4) {
        std::cout << "M";
        --aux;
    }
    switch (centenas) {
        case 1 :
            std::cout << "C";
            break;
        case 2 :
            std::cout << "CC";
            break;
        case 3 :
            std::cout << "CCC";
            break;
        case 4:
            std::cout << "CD";
            break;
        case 5:
            std::cout << "D";
            break;
        case 6 :
            std::cout << "DC";
            break;
        case 7 :
            std::cout << "DCC";
            break;
        case 8:
            std::cout << "DCCC";
            break;
        case 9:
            std::cout << "CM";
            break;
    }
    switch (decenas) {
        case 1 :
            std::cout << "X";
            break;
        case 2 :
            std::cout << "XX";
            break;
        case 3 :
            std::cout << "XXX";
            break;
        case 4:
            std::cout << "XL";
            break;
        case 5:
            std::cout << "L";
            break;
        case 6 :
            std::cout << "LX";
            break;
        case 7 :
            std::cout << "LXX";
            break;
        case 8:
            std::cout << "LXXX";
            break;
        case 9:
            std::cout << "XC";
            break;
    }
    switch (unidades) {
        case 1 :
            std::cout << "I";
            break;
        case 2 :
            std::cout << "II";
            break;
        case 3 :
            std::cout << "III";
            break;
        case 4:
            std::cout << "IV";
            break;
        case 5:
            std::cout << "V";
            break;
        case 6 :
            std::cout << "VI";
            break;
        case 7 :
            std::cout << "VII";
            break;
        case 8:
            std::cout << "VIII";
            break;
        case 9:
            std::cout << "IX";
            break;
        }
}