Question

Write a C++ program which reads a string, less than 10 characters long. This string represents
an integer expressed in roman numbers. Let a function convert the number from roman to
arabic form (i.e., our standard digits). Let then the main program writes out both forms. The
roman numbers are written according to: M = 1000, D = 500, C =100, L=50, X=10, V=5, I=1.
Examples:
LXXXVII = 87
CCXIX = 219
MCCCLIV = 1354
MMDCLXXIII = 2673

Answer 1

Code:

#include <bits/stdc++.h>
using namespace std;

int count(char n)
{
   if (n == 'I')
       return 1;
   if (n == 'V')
       return 5;
   if (n == 'X')
       return 10;
   if (n == 'L')
       return 50;
   if (n == 'C')
       return 100;
   if (n == 'D')
       return 500;
   if (n == 'M')
       return 1000;

   return -1;
}

//function to convert from Roman to Arabic
int convert(string& x)
{
   //initializing m=0 to store the result
   int m = 0;

   for (int j = 0; j < x.length(); j++) {
       //a[j]'s value
       int a = count(x[j]);

       if (j + 1 < x.length()) {
           // a[j+1]'s value
           int b = count(x[j + 1]);

           //evaluating a and b
           if (a >= b) {
               m = m + a;
           }
           else {
               m = m + b - a;
               j++;
           }
       }
       else {
           m = m + a;
       }
   }
   return m;
}

//Main
int main()
{
   //reading the string
   string x = "MMDCLXXIII";
   //if condtion to check the length of the string
   if (x.length()>10){
        //if length of the string is greater than 10. program will print
        //invalid input
        cout<<"Invalid Input. Input must be less than 10 characters"<<endl;
   }
   else{
        //printing the output in both forms
   cout <<"Roman Number    Arabic Number"<<endl;
   cout << x<< "       =        "<< convert(x) << endl;
   }

   return 0;
}

Explanation:

The above C++ program reads a string less than 10 characters which represents a Roman number

and convert it to the Arabic form

This program consists of a Function named "convert" and main function

and prints the output in both forms i.e Roman and Arabic form in the main function.

if the string is longer than 10 characters , the program will print the output as "Invalid input"

Screenshots of the Code:

Screenshots of the Output:

If the String is longer than 10 characters. Then output is: