Write a program that converts a Roman number such as MCMLXXVIII to its decimal n

Question

Write a program that converts a Roman number such as MCMLXXVIII to its decimal number representation that uses the following functions:

int romanCharValue(char r): yields the numeric value of the passed Roman numeral character.

int convertRomanToInt(string s): this function converts the Roman number string into its equivalent integer value by implementing the following algorithm.

total = 0

While the roman number string is not empty

      If the first character has a larger or equal value than the second, or the string has length 1

            Add value(first character) to total.

            Remove the character.

      Else

            Add the quantity: value(second character) - value(first character)   to total.

            Remove both characters.

Provide a program that tests your functions via a loop construct for acquiring testing data.

Example run (with user input indicated with bold italics):

Enter Roman number or Q to quit: I

I = 1

Enter Roman number or Q to quit: V

V = 5

Enter Roman number or Q to quit: X

X = 10

Enter Roman number or Q to quit: L

L = 50

Enter Roman number or Q to quit: C

C = 100

Enter Roman number or Q to quit: D

D = 500

Enter Roman number or Q to quit: M

M = 1000

Enter Roman number or Q to quit: MCMLXII

MCMLXII = 1962

Enter Roman number or Q to quit: MDCCCLXXXVIII

MDCCCLXXXVIII = 1888

Enter Roman number or Q to quit: Q

Explanation / Answer

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

int romanCharValue(char r)
{
if(r == 'M')
return 1000;
else if(r == 'D')
return 500;
else if(r == 'C')
return 100;
else if(r == 'L')
return 50;
else if(r == 'X')
return 10;
else if(r == 'V')
return 5;
else if(r == 'I')
return 1;
return 0;   
}

int convertRomanToInt(string s)
{
int i, total = 0;
char c, cnext;
for (i=0; i<(s.length()-1); ++i)
{
c= s.at(i);
cnext = s.at(i + 1);
if(romanCharValue(c) >= romanCharValue(cnext))
{
total += romanCharValue(c);
}
else
{
total += (romanCharValue(cnext) - romanCharValue(c));
i++;
}   
}
total += romanCharValue(s.at(i));
return total;
}

  
int main()
{
string roman;
while(1)
{
cout<<"Enter Roman number or Q to quit: ";
cin>>roman;
if(roman.at(0) == 'Q')
exit(0);
cout<<roman<<" = "<<convertRomanToInt(roman)<<endl;
}
}

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