How to create a CLASS at runtime in .NET using C#?

static void Main()
    {
        TestExpression("2+1-(3*2)+8/2");
        TestExpression("1*2*3*4*5*6");
        TestExpression("Invalid expression");
    }
    static void TestExpression(string expression)
    {
        try
        {
            int result = EvaluateExpression(expression);
            Console.WriteLine("'" + expression + "' = " + result);
        }
        catch (Exception)
        {
            Console.WriteLine("Expression is invalid: '" + expression + "'");
        }
    }
    public static int EvaluateExpression(string expression)
    {
        string code = string.Format("public static class Func{{ public static int func(){{ return {0};}}}}", expression);
        CompilerResults compilerResults = CompileScript(code);
        if (compilerResults.Errors.HasErrors)
        {
            throw new InvalidOperationException("Expression has a syntax error.");
        }
        Assembly assembly = compilerResults.CompiledAssembly;
        MethodInfo method = assembly.GetType("Func").GetMethod("func");
        return (int)method.Invoke(null, null);
    }

    public static CompilerResults CompileScript(string source)
    {

        CompilerParameters parms = new CompilerParameters();
        parms.GenerateExecutable = false;
        parms.GenerateInMemory = true;
        parms.IncludeDebugInformation = false;
        CodeDomProvider compiler = CSharpCodeProvider.CreateProvider("CSharp");
        return compiler.CompileAssemblyFromSource(parms, source);
    }