int d = 0;

switch(ch){

case 'I':

d = 1;

break;

case 'V':

d = 5;

break;

case 'X':

d = 10;

break;

case 'L':

d = 50;

break;

case 'C':

d = 100;

break;

case 'D':

d = 500;

break;

case 'M':

d = 1000;

break;

}

return d;

if (s.size()<=0) return 0;

int result = romanCharToInt(s[0]);

for (int i=1; i<s.size(); i++){

int prev = romanCharToInt(s[i-1]);

int curr = romanCharToInt(s[i]);

//if left<right such as : IV(4), XL(40), IX(9) ...

if (prev < curr) {

result = result - prev + (curr-prev);

}else{

result += curr;

}

}

return result;

{

string s("XL");

if (argc>1){

s = argv[1];

}

cout << s << " : " << romanToInt(s) << endl;

return 0;