Author: Peter Thörnqvist

How to convert roman notation to a numeric value

Answer:

1   function RomanToDec(const Value: string): integer;
2   var
3     i, lastValue, curValue: integer;
4   begin
5     Result := 0;
6     lastValue := 0;
7     for i := Length(Value) downto 1 do
8     begin
9       case UpCase(Value[i]) of
10        'C':
11          curValue := 100;
12        'D':
13          curValue := 500;
14        'I':
15          curValue := 1;
16        'L':
17          curValue := 50;
18        'M':
19          curValue := 1000;
20        'V':
21          curValue := 5;
22        'X':
23          curValue := 10;
24      else
25        raise Exception.CreateFmt('Invalid character: %s', [Value[i]]);
26      end;
27      if curValue < lastValue then
28        Dec(Result, curValue)
29      else
30        Inc(Result, curValue);
31      lastValue := curValue;
32    end;
33  end;