C#: how to pass mathematical function from textbox to function

Question

I have a textbox where i want to read user-input mathematical functions( ex: Math.Sqrt(x) etc).

The code I've been using for console testing the function is

    static double f(double x)
    {
        double f;
        f = Math.Sqrt(x);
        return f;
    }

I'm not sure how to modify it: do I read the textbox contents in a string, and add that string as a second argument to the f function ( static double f(double x, string s)? what type of parsing should I apply to the string?

Does the user always enter C#-compiling arithmetics and math? — SimpleVar, May 08 '12 at 06:33

Uwe Keim · Accepted Answer · 2012-05-08T06:39:18.550

5

There are several formula parsers out there that you can use.

Basically you need someone/something that evaluates your formula.

I'm using this one successfully in my own projects. It allows for calling it like

var ev = 
    new Eval3.Evaluator(
        Eval3.eParserSyntax.c,/*caseSensitive*/ 
        false);

MessageBox.Show(ev.Parse("1+2+3").value.ToString());

What I would not recommend to use is the dynamic compilation of C# code since it adds each compiled code to your application domain ("app domain") and there is no option to unload it again. (Correct me, if I'm wrong).

edited May 08 '12 at 06:39

answered May 08 '12 at 06:33

Uwe Keim

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1

thank you, dunno why I didn't think of searching for something like this. I'll give the parser a shot, thanks – user573382 May 08 '12 at 06:39

score 1 · Answer 2 · answered May 08 '12 at 06:37

1

Another evaluator: http://csharp-eval.com/

answered May 08 '12 at 06:37

David Brabant

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score 0 · Answer 3 · answered May 08 '12 at 06:39

If your interested in how to get the text from the textbox and do something with the value the following code will do that for you. If you want to enter a function in the textbox - sqrt(40) you should check this project: http://www.codeproject.com/Articles/23061/MathParser-Math-Formula-Parser

http://msdn.microsoft.com/en-us/library/system.windows.forms.textbox.aspx

static double f(Textbox tb)
{
    double f;
    double x = Double.Parse(tb.Text);
    f = Math.Sqrt(x);
    return f;
}

score 0 · Answer 4 · answered May 08 '12 at 06:39

You can execute arbitrary code, but not easily. For general code you must create a wrapper class and insert the code into a function.

Take a look at http://social.msdn.microsoft.com/forums/en-US/csharpgeneral/thread/6a783cc4-bb54-4fec-b504-f9b1ed786b54/

C#: how to pass mathematical function from textbox to function

4 Answers4