/// <summary>
/// Counts an expression
/// </summary>
/// <param name="expression">Expression</param>
/// <param name="stack">Stack which is used to count an expression</param>
/// <returns>Pair of expression value and boolean. False if there was an error</returns>
public static (double, bool) CountAnExpression(string expression, IStack stack)
{
string[] numbers = expression.Split(' ', StringSplitOptions.RemoveEmptyEntries);
for (int i = 0; i < numbers.Length; i++)
{
bool isNumber = int.TryParse(numbers[i], out int number);
if (isNumber)
{
stack.Push(number);
}
else
{
if (stack.Empty)
{
return (0, false);
}
double second = stack.Pop();
if (stack.Empty)
{
return (0, false);
}
double first = stack.Pop();
switch (numbers[i])
{
case "+":
stack.Push(first + second);
break;
case "-":
stack.Push(first - second);
break;
case "*":
stack.Push(first * second);
break;
case "/":
if (Math.Abs(second - 0) < 1e-6)
{
stack.ClearStack();
return (0, false);
}
stack.Push(first / second);
break;
default:
stack.ClearStack();
return (0, false);
};
}
}
double result = stack.Pop();
return stack.Empty ? (result, true) : (0, false);
}