Roman Numeral Calculator

I'm a noob programmer and wrote this for practice, it's kind of cool though if you happen to have a compiler and all that and want to check it out.  I haven't built in the part to convert the answer back to Roman Numerals yet, and there isn't a way to verify that what you input are legitimate Roman Numerals either, it just takes whatever you put in and tries to make sense of it, so if the input numbers are bogus the output will be too.  Makes sense. 

Here's what the output looks like:

Nothing flashy, but it's functional.  


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

char RomanNumeral[10];
float numberarray[10];
float number1, number2;
float ans;
float convert();
float temp = 0;
int again();

int main()
{
     cout << "Roman Numeral Calculator\n\n";
     cout << "_____________________________

__\n\n";
     cout << "Enter the first Roman Numeral:  ";
     convert();
     number1 = temp;
     cout <<"\nEnter +, -, *, or /: ";   //add, subtract...etc. 
     char action;
     cin >> action;
     cout << "\nEnter the second Roman Numeral: ";
     convert();
     number2 = temp;

     

    //Perform the selected action on the two numbers
     if(action == '+')
         ans = number1 + number2;
    else if(action == '-')
         ans = number1 - number2;
    else if(action == '*')
         ans = number1 * number2;
    else if(action == '/')
         ans = number1 / number2;
    else
         {cout<<"Error, please try again";
    main();}

cout<<dec<<"Answer: "<<ans<<endl;
again();
return 0;
} //end main

float convert()
{
    for(int y = 0; y < 10; ++y)  //reset the arrays
        {
            RomanNumeral[y] = 0;
            numberarray[y] = 0;
        }
    cin >> RomanNumeral;        //get user input

for(int y = 0; y <= 10; ++y)   //Populate the number array with decimal values, allowing for upper or lowercase roman numeral entries
    {
        if((RomanNumeral[y] == 'I') || (RomanNumeral[y] == 'i'))
            {numberarray[y] = 1;}
        else if((RomanNumeral[y] == 'V')||(RomanNumeral[y] == 'v'))
            {numberarray[y] = 5;}
        else if((RomanNumeral[y] == 'X')||(RomanNumeral[y] == 'x'))
            {numberarray[y] = 10;}
        else if((RomanNumeral[y] == 'L')||(RomanNumeral[y] == 'l'))
            {numberarray[y] = 50;}
        else if((RomanNumeral[y] == 'C')||(RomanNumeral[y] == 'c'))
            {numberarray[y] = 100;}
        else if((RomanNumeral[y] == 'D')||(RomanNumeral[y] == 'd'))
            {numberarray[y] = 500;}
        else if((RomanNumeral[y] == 'M')||(RomanNumeral[y] == 'm'))
            {numberarray[y] = 1000;}
    }

temp = numberarray[0]; //set the variable equal to the first value in the number array

for(int y = 1; y < 10; ++y)  //This is where the magic happens
    {
        if(numberarray[y] > numberarray[y-1])
            temp += (numberarray[y] - 2*numberarray[y-1]);  //the 2 multiplier is key.  without it the program adds the value back in and ruins the answer.
        else if(numberarray[y] < numberarray[y-1])
            temp += numberarray[y];
        else if(numberarray[y] == numberarray[y-1])
            temp += numberarray[y];
    }
cout<<"\nDecimal equivalent = "<<temp<<endl;

return(temp);  //Send decimal equivalent back to main
} //end convert

int again() //Run main again or bail out of the program
{
char selection;
cout<<endl<<"Another calculation? y/n ";
cin >>selection;
if((selection == 'y')||selection == 'Y')
    {
        for(int y = 0; y<10; ++y)
            {
                numberarray[y] = 0;      //reset numberarray to all zeros
                RomanNumeral[y] = 0; //reset letterarray
            }
        number1 = 0;
        number2 = 0;
        temp = 0;                            //everything is reset to zero for next round
        main();
    }
else
    {
        cout<<endl;
        cin.ignore();
        system("pause");
    }
return 0;
} // end again