Hello,

I usually program in C++ and I only know the basics of C#. I used C# once to write a simple game using XNA. I've been wanting to do a bit more C# programming lately and I thought this problem sounded interesting.

I decided to see if I could write a C# command line program that would take a basic equation and solve it. I was able to make a very basic calculator. It doesn't take into account operator precedence or invalid input.

Here is the code:


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

// Very basic calculator
// Doesn't handle operator precedence or invalid input
namespace SimpleCalculator
{
class Program
{
static void Main(string[] args)
{
string userInput = ""; // stores user input

// Loop until the user types 'exit'
while (userInput != "exit")
{
// Get user input
Console.Write("Please enter your equation: ");
userInput = Console.ReadLine();
if (userInput == "exit") {
break; // done
}

// You may now have a string like this: 42 + 43 - 47 + 32 / 5 * 2
// or like this: 4 2 +43 - 4 7 + 32 /5* 2
//
// or with decimals like this: 12.5 + 3.5 /3
// or even like this: 12. 5 +3 .5 / 3

// Remove all the spaces
userInput = userInput.Replace(" ", "");

// Use RegEx to Split the strings
System.Text.RegularExpressions.Regex rNums = new System.Text.RegularExpressions.Regex("[+]|[-]|[/]|

");
System.Text.RegularExpressions.Regex rSigns = new System.Text.RegularExpressions.Regex("[0-9]+[.]?[0-9]?");

// Split the numbers and signs into their own lists
List<string> explodedNums = rNums.Split(userInput).ToList<string>();
List<string> explodedSigns = rSigns.Split(userInput).ToList<string>();
explodedSigns.RemoveAll(item => item == ""); //

// Show the separated numbers
Console.WriteLine("\nNumbers");
Console.WriteLine("=======");
foreach (string match in explodedNums)
{
Console.WriteLine("'{0}'", match);
}

// Show the separated signs
Console.WriteLine("\nSigns");
Console.WriteLine("=====");
foreach (string match in explodedSigns)
{
Console.WriteLine("'{0}'", match);
}

//
double operand1, operand2 = 0.0;

// Get the first number
operand1 = System.Convert.ToDouble(explodedNums[0]);

// For every other number
for (int i = 1, j = 0; i < explodedNums.Count; i++, j++)
{
Console.Write("\n{0} ", operand1); // show first part of equation

// Get the next number
operand2 = System.Convert.ToDouble(explodedNums);

// Perform the operation
switch (explodedSigns[j])
{
case "+":
{
operand1 += operand2;
break;
}
case "-":
{
operand1 -= operand2;
break;
}
case "/":
{
operand1 /= operand2;
break;
}
case "*":
{
operand1 *= operand2;
break;
}
}

// Show final part of equation
Console.Write("{0} {1} = {2}", explodedSigns[j], operand2, operand1);
}

// Show the answer
Console.WriteLine("\n\nYour final answer is: " + operand1 + "\n");

} // while loop

} // Main()

} // class

} // namespace