ReversePolishNotation

HomeworkClasses

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Threading;

class CalculateArithExpression
{
    static List<string> operators = new List<string>();
    static List<string> allTokens = new List<string>();
    static string[][] priority = {
                                 new string[]{ "ln", "sqrt", "pow"},
                                 new string[]{ "*", "/"}, 
                                 new string[] {"+", "-" }
                                 };
    static void Main()
    {
        //Console.WriteLine("Enter the expression:");
        //string expression = Console.ReadLine();
        Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
        string expression = "(3+5.3) * 2.7 - ln(22) / pow(2.2, -1.7)";
        //string expression = "7+3*(4+2*(3-4+2-(4+3)+1))";
        for (int i = 0; i < expression.Length; i++)
        {
            if (expression[i]==' ')
            {
                expression=expression.Remove(i, 1);
                i--;
            }
        }
        //List<string> finalList = ReturnStack(expression);
        ReturnStack(expression);
        //for (int i = 0; i < allTokens.Count; i++)
        //{
        //    Console.WriteLine(allTokens[i]);
        //}
        double finalRezult=CalculateStack();
        Console.WriteLine("The rezult is: {0}",finalRezult);
    }

    static void ReturnStack(string expression)
    {
        for (int i = 0; i < expression.Length; i++)
        {
            string tmpNumber = String.Empty;
            bool checkForMinusNumber = (expression[i] == '-'&&(i==0||expression[i-1]==','||expression[i-1]=='('));
            if (CheckForNumber(Convert.ToString(expression[i]))||checkForMinusNumber)
            {
                tmpNumber = Convert.ToString(expression[i]);
                while (CheckForNumber(Convert.ToString(expression[i + 1])) || expression[i + 1] == '.')
                {
                    i++;
                    tmpNumber += Convert.ToString(expression[i]);
                }
                allTokens.Add(tmpNumber);
            }
            switch (expression[i])
            {
                case 'p':
                    operators.Add("pow");
                    i += 2;
                    break;
                case 's':
                    operators.Add("sqrt");
                    i += 3;
                    break;
                case 'l':
                    operators.Add("ln");
                    i++;
                    break;
                case'(':
                    operators.Add("(");
                    break;
                case ')':
                    ArrangeListsIfRightBracket(operators.Count-1);
                    break;
                case '+':
                case '-':
                case '*':
                case '/':
                    ArrangeDependsPriority(expression[i], operators.Count - 1);
                    break;
            }
        }
        while (operators.Count>0)
        {
            allTokens.Add(operators[operators.Count-1]);
            operators.RemoveAt(operators.Count - 1);
        }
        //return allTokens;
    }

    static bool CheckForNumber(string digitOrNumber)
    {
        double tempDigit = 0;
        bool isNumber = double.TryParse(digitOrNumber, out tempDigit);
        return isNumber;
    }

    static void ArrangeListsIfRightBracket(int index)
    {
        while (operators[index]!="(")
        {
            allTokens.Add(operators[index]);
            operators.RemoveAt(index);
            index--;
        }
        operators.RemoveAt(index);
    }

    static void ArrangeDependsPriority(char currOperator,int previousIndex)
    {
        while (previousIndex >= 0 && operators[previousIndex] != "(")
        {
            int currOperPrior = -1;
            int prevOperPrior = -1;
            for (int i = 0; i < priority.GetLength(0); i++)
            {
                if (Array.IndexOf(priority[i], Convert.ToString(currOperator)) > -1)
                {
                    currOperPrior = i;
                }
                if (Array.IndexOf(priority[i], operators[previousIndex]) > -1)
                {
                    prevOperPrior = i;
                }
            }
            if (prevOperPrior<=currOperPrior)
            {
                allTokens.Add(operators[previousIndex]);
                operators.RemoveAt(previousIndex);
                previousIndex--;
            }
            else
            {
                break;
            }
        }
        operators.Add(Convert.ToString(currOperator));
    }

    static double CalculateStack()
    {
        double tmpRezult = 0.0;
        int counter = 0;
        while (allTokens.Count > 1)
        {
            if (!CheckForNumber(allTokens[counter]))
            {
                switch (allTokens[counter])
                {
                    case "pow":
                        tmpRezult = Math.Pow(double.Parse(allTokens[counter - 2]), 
                            double.Parse(allTokens[counter - 1]));
                        allTokens.RemoveAt(counter);
                        allTokens.Insert(counter, Convert.ToString(tmpRezult));
                        allTokens.RemoveAt(counter-1);
                        allTokens.RemoveAt(counter-2);
                        break;
                    case "sqrt":
                        tmpRezult=Math.Sqrt(double.Parse(allTokens[counter-1]));
                        allTokens.RemoveAt(counter);
                        allTokens.Insert(counter, Convert.ToString(tmpRezult));
                        allTokens.RemoveAt(counter-1);
                        break;
                    case "ln":
                        tmpRezult=Math.Log(double.Parse(allTokens[counter-1]));
                        allTokens.RemoveAt(counter);
                        allTokens.Insert(counter, Convert.ToString(tmpRezult));
                        allTokens.RemoveAt(counter-1);
                        break;
                    case "+":
                         tmpRezult = double.Parse(allTokens[counter - 2])+ 
                            double.Parse(allTokens[counter - 1]);
                        allTokens.RemoveAt(counter);
                        allTokens.Insert(counter, Convert.ToString(tmpRezult));
                        allTokens.RemoveAt(counter-1);
                        allTokens.RemoveAt(counter-2);
                        break;
                    case "-":
                        tmpRezult = double.Parse(allTokens[counter - 2])- 
                            double.Parse(allTokens[counter - 1]);
                        allTokens.RemoveAt(counter);
                        allTokens.Insert(counter, Convert.ToString(tmpRezult));
                        allTokens.RemoveAt(counter-1);
                        allTokens.RemoveAt(counter-2);
                        break;
                    case "*":
                        tmpRezult = double.Parse(allTokens[counter - 2])* 
                            double.Parse(allTokens[counter - 1]);
                        allTokens.RemoveAt(counter);
                        allTokens.Insert(counter, Convert.ToString(tmpRezult));
                        allTokens.RemoveAt(counter-1);
                        allTokens.RemoveAt(counter-2);
                        break;
                    case "/":
                        tmpRezult = double.Parse(allTokens[counter - 2])/ 
                            double.Parse(allTokens[counter - 1]);
                        allTokens.RemoveAt(counter);
                        allTokens.Insert(counter, Convert.ToString(tmpRezult));
                        allTokens.RemoveAt(counter-1);
                        allTokens.RemoveAt(counter-2);
                        break;
                }
                counter = 0;
            }
            else
            {
                counter++;
            }
        }
        return tmpRezult;
    }
}