Making roman numerals into arabic numbers

I'm trying to write a program that takes roman numbers and outputs regular arabic numbers.
I'm having trouble with the numbers such as 4 (IV), 9 (IX), 40 (XL),
90 (XC) and so on.
I tried the if statement:
if(rome[i] == 'C' && rome[(i)+1] =='M')
I'm attaching the code so you can see it all,
Any suggestions?

Well the way you have it, IX will be 19, not 9.When you check for the two number such as IX, increment i, so it goes to the next letter after X. Same with the other double values.

So:

Code:

---

int i;
for(i = 0; i < thing.length(); i++)
{
if(thing[i] = 'I' && thing[i + 1] == 'X')
{
  a = 9;
    i++;
}
/* ... */

---

You've got it down pretty well, keep trying. You should post the main code, it's not that big...

Also you don't need to include fstream and cmath...