How can i get a result in my Roman numeral to decimal converter?

#include <iostream>
#include <string>
using namespace std;

class rom2dec
{ 
    public: void roman(); 
    int convert(); 
    void print(); 
    void get(); 
    private: int M, D, C, L, X, V, I; 
    char romanNumeral; 
};
    void rom2dec::roman()
{ 
    M = 1000; 
    D = 500; 
    C = 100; 
    L = 50; 
    X = 10; 
    V = 5; 
    I = 1; 
} 
    int rom2dec::convert()
{ 
    if(romanNumeral == 'I' || 'i')
    { cout << 1; }
    else if(romanNumeral == 'V' || 'v')
    { cout << 5; }
    else if(romanNumeral == 'X' || 'x')
    { cout << 10; }
    else if(romanNumeral == 'L' || 'l')
    { cout << 50; }
    else if(romanNumeral == 'C' || 'c')
    { cout << 100; }
    else if(romanNumeral == 'D' || 'd')
    { cout << 500; }
    else if (romanNumeral == 'M' || 'm')
    { cout << 1000; }
    else if(romanNumeral != 'I' && romanNumeral != 'i' && romanNumeral !=  'V' && romanNumeral != 'v' && romanNumeral != 'X' && romanNumeral != 'x' && romanNumeral != 'L' && romanNumeral != 'l' && romanNumeral != 'C' && romanNumeral != 'c' && romanNumeral != 'D' && romanNumeral != 'd' && romanNumeral != 'M' && romanNumeral != 'm')
    { cout << "Error! Not a valid value!" << endl; }
    return romanNumeral; 
}

    void rom2dec::print()
    { cout << romanNumeral << endl; }
    void rom2dec::get(){ }

int main()
{
    char romanNumeral; 
    cout << "Please enter a number in Roman numerals to be converted: " << endl; 
    cin >> romanNumeral;  
    return 0;
}

I get no errors when I build the program, but when I debug and try to convert a Roman numeral to a decimal I get no decimal. All suggestions welcome and if there is a simpler way to write the last else if please let me know. Thanks.