private static CalculationResult CalculateByRPN(string input)
{
var result = 0.0;
var number = 0.0;
var digitStack = new Stack <double>();
var symbols = input.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
for (int i = 0; i < symbols.Length; i++)
{
if (double.TryParse(symbols[i], System.Globalization.NumberStyles.Float,
System.Globalization.CultureInfo.InvariantCulture, out number))
{
digitStack.Push(number);
}
else
{
if (digitStack.Count() >= 2)
{
double secondArgument = digitStack.Pop();
if (secondArgument == 0 && symbols[i] == "/")
{
return(CalculationResult.CreateError("Division by zero"));
}
double firstArgument = digitStack.Pop();
switch (symbols[i])
{
case "+":
result = firstArgument + secondArgument;
break;
case "-":
result = firstArgument - secondArgument;
break;
case "*":
result = firstArgument * secondArgument;
break;
case "/":
result = firstArgument / secondArgument;
break;
case "^":
result = Math.Pow(firstArgument, secondArgument);
break;
}
}
else
{
return(CalculationResult.CreateError("Invalid notation"));
}
digitStack.Push(result);
}
}
return(CalculationResult.CreateSuccess(digitStack.Peek()));
}
public static CalculationResult Calculate(string input)
{
var validationError = ValidateInput(input);
if (validationError != null)
{
return(CalculationResult.CreateError(validationError));
}
string rpn;
string error;
if (!TryGetReversePolishNotation(input, out rpn, out error))
{
return(CalculationResult.CreateError(error));
}
return(CalculateByRPN(rpn));
}