How to evaluate a math expression contained in a string?

[Juan]

If I have a string with a valid math expression like " (2 + 28)/1", how can
I evaluate it?



Thanks,

Juan.

 

[Guest]

You can always work hard and write it yourself, but I think you are not the
first to meet this. I found something in CodeProject:
http://www.codeproject.com/vb/net/math_expression_evaluator.asp
I you search yourself, I'm sure you'll find more.

 

[James Curran]

Try the .Math library:
http://hebertsoft.com/dotmath/ (Note, he's moving the downloads from
http://workspaces.gotdotnet.com/math to
https://sourceforge.net/projects/dotmath/, but is still in the process)

 

[Jako Menkveld]

I'm not sure how safe this is, but I used this in a non-production
environment and it works quite well:

 

[Jako Menkveld]

Sorry about that, here's the code:

------------------------------------------------------------------------------
using System;

using Microsoft.JScript;
using Microsoft.JScript.Vsa;

namespace VPDBUtils
{
public class JScriptEvaluator
{
private static VsaEngine vsaEngine;

public static void Initialize()
{
vsaEngine = VsaEngine.CreateEngine();
}

public static void Close()
{
if (vsaEngine != null)
{
vsaEngine.Close();
}
}

private static object EvaluateString(string sStringToEvaluate)
{
return Eval.JScriptEvaluate(sStringToEvaluate, vsaEngine);
}

internal static double EvaluateStringAsDouble(string sStringToEvaluate)
{
return System.Convert.ToDouble(EvaluateString(sStringToEvaluate));
}
}
}