Talk:Parsing/RPN calculator algorithm: Difference between revisions
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=={{header|C sharp|C#}}== |
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<lang csharp> |
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using System; |
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using System.Collections.Generic; |
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using System.Linq; |
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using System.Globalization; |
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using System.Threading; |
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namespace RPNEvaluator |
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{ |
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class RPNEvaluator |
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{ |
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static void Main(string[] args) |
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{ |
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Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture; |
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string rpn = "3 4 2 * 1 5 - 2 3 ^ ^ / +"; |
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Console.WriteLine("{0}\n", rpn); |
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decimal result = CalculateRPN(rpn); |
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Console.WriteLine("\nResult is {0}", result); |
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} |
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static decimal CalculateRPN(string rpn) |
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{ |
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string[] rpnTokens = rpn.Split(' '); |
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Stack<decimal> stack = new Stack<decimal>(); |
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decimal number = decimal.Zero; |
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foreach (string token in rpnTokens) |
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{ |
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if (decimal.TryParse(token, out number)) |
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{ |
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stack.Push(number); |
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} |
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else |
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{ |
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switch (token) |
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{ |
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case "^": |
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case "pow": |
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{ |
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number = stack.Pop(); |
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stack.Push((decimal)Math.Pow((double)stack.Pop(), (double)number)); |
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break; |
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} |
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case "ln": |
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{ |
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stack.Push((decimal)Math.Log((double)stack.Pop(), Math.E)); |
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break; |
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} |
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case "sqrt": |
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{ |
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stack.Push((decimal)Math.Sqrt((double)stack.Pop())); |
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break; |
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} |
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case "*": |
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{ |
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stack.Push(stack.Pop() * stack.Pop()); |
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break; |
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} |
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case "/": |
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{ |
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number = stack.Pop(); |
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stack.Push(stack.Pop() / number); |
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break; |
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} |
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case "+": |
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{ |
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stack.Push(stack.Pop() + stack.Pop()); |
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break; |
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} |
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case "-": |
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{ |
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number = stack.Pop(); |
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stack.Push(stack.Pop() - number); |
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break; |
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} |
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default: |
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Console.WriteLine("Error in CalculateRPN(string) Method!"); |
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break; |
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} |
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} |
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PrintState(stack); |
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} |
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return stack.Pop(); |
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} |
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static void PrintState(Stack<decimal> stack) |
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{ |
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decimal[] arr = stack.ToArray(); |
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for (int i = arr.Length - 1; i >= 0; i--) |
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{ |
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Console.Write("{0,-8:F3}", arr[i]); |
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} |
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Console.WriteLine(); |
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} |
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} |
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}</lang> |
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Output: |
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<pre> |
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3 4 2 * 1 5 - 2 3 ^ ^ / + |
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3.000 |
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3.000 4.000 |
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3.000 4.000 2.000 |
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3.000 8.000 |
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3.000 8.000 1.000 |
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3.000 8.000 1.000 5.000 |
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3.000 8.000 -4.000 |
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3.000 8.000 -4.000 2.000 |
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3.000 8.000 -4.000 2.000 3.000 |
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3.000 8.000 -4.000 8.000 |
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3.000 8.000 65536.000 |
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3.000 0.000 |
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3.000 |
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Result is 3.0001220703125 |
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</pre> |
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