Mega Code Archive
Converting roman notation to a numeric value
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Title: Converting roman notation to a numeric value
Question: Carlos Alberto Longen wrote a nice article on converting a numeric value into roman notation. This is the complement function, going the other way.
Minor update: arranging the items of the case statement in ASCII order makes it slightly faster. Inc and Dec also improves speed a little (not that it really is needed, but it looks better...)
Answer:
function RomanToDec(const Value:string):integer;
var i,lastValue,curValue:integer;
begin
Result := 0;
lastValue := 0;
for i := Length(Value) downto 1 do
begin
case UpCase(Value[i]) of
'C':
curValue := 100;
'D':
curValue := 500;
'I':
curValue := 1;
'L':
curValue := 50;
'M':
curValue := 1000;
'V':
curValue := 5;
'X':
curValue := 10;
else
raise Exception.CreateFmt('Invalid character: %s',[Value[i]]);
end;
if curValue Dec(Result,curValue)
else
Inc(Result,curValue);
lastValue := curValue;
end;
end;
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