Re: [DOTNET] Evaluate math expression strings?

[Alexandre G. Valente]

Hi, if you want to dinamically compile the expression, you can use
something like this:

private object CreateMyMath(string sExpression)
{
        StringWriter sw = new StringWriter();
        // Source Code
        sw.WriteLine("using System;");
        sw.WriteLine("using System.Collections;");

        sw.WriteLine("public class MyMath");
        sw.WriteLine("{");
        sw.WriteLine("  public decimal Evaluate()");
        sw.WriteLine("  {");
        sw.WriteLine("          return " + sExpression + ";");
        sw.WriteLine("  }");
        sw.WriteLine("}");
        Microsoft.CSharp.CSharpCodeProvider cs = new
Microsoft.CSharp.CSharpCodeProvider();
        System.CodeDom.Compiler.ICodeCompiler ic = cs.CreateCompiler();
        System.CodeDom.Compiler.CompilerParameters cp = new
System.CodeDom.Compiler.CompilerParameters();
        System.CodeDom.Compiler.CompilerResults Results =
ic.CompileAssemblyFromSource(cp, sw.ToString());
        return Results.CompiledAssembly.CreateInstance("MyMath");
}

And use it like this:

object MyMath = CreateMyMath(sExpression);
return (decimal) MyMath.GetType().GetMethod("Evaluate").Invoke(MyMath ,
null);

-----Original Message-----
From: dotnet discussion [mailto:[EMAIL PROTECTED]] On Behalf Of
Aaron Fanetti
Sent: Sunday, April 14, 2002 12:47 AM
To: [EMAIL PROTECTED]
Subject: [DOTNET] Evaluate math expression strings?


Does the framework have (or is someone willing to share :) ) a utility
class to do this? Or will I need to build my own interpreter? Something
like...

int result = MyMath.Evaluate( "(10 / 2) * 3" );

Thanks,
Aaron

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