C#

Question: 1
Suppose using controls in Visual Studio you have developed the layout for a calculator in design mode as shown
below, and given names of button Add, Subtract, Multiply and divide as Plusbtn, Subbtn, Mulbtn and Divbtn
respectively. Names for TextBox labeled First Number, Second Number and Result are textBox1, textBox2 and
textBox3 respectively. If a number is entered in TextBox1 and TextBox2, clicking the buttons should produce result
of respective operation in TextBox3. Complete the code

DataTable loDataTable = new DataTable();
DataColumn loDataColumn = new DataColumn("Eval", typeof(double), expression);
loDataTable.Columns.Add(loDataColumn);
loDataTable.Rows.Add(0);
return (UInt32)(double)(loDataTable.Rows[0]["Eval"]);

public static bool parseDifficultExpression(string difficultExpression, out UInt32 parsedValue)
{
    try
    {
        string[] usingList = new string[] { "System",
                                            "System.Text",
                                            "System.Diagnostics" };
        string methodAsString = "    returnValue = " + difficultExpression + ";";
        string notUsed = "";
        parsedValue = (UInt32)Utilities.executeMethodAsString(usingList, methodAsString, notUsed, typeof(UInt32));
        return true;
    }
    catch (Exception)
    {
        parsedValue = 0xFFFFFFFF;
        return false;
    }
}

public static object executeMethodAsString(string[] usingList, string methodAsString, object args, Type returnType)
{
    string[] importList = new string[] { "System.dll" };
    string namespaceName = "myNameSpace";
    string className = "myClass";
    string methodName = "myMethod";

    //Create method
    CodeMemberMethod pMethod = new CodeMemberMethod();
    pMethod.Name = methodName;
    pMethod.Attributes = MemberAttributes.Public;
    pMethod.Parameters.Add(new CodeParameterDeclarationExpression(args.GetType(), "args"));
    pMethod.ReturnType = new CodeTypeReference(typeof(UInt32));
    string completeMethod =
        returnType + " returnValue = new " + returnType + "();" + "\r\n" +
        "try {"                                                 + "\r\n" +
            methodAsString                                      + "\r\n" +
        "} catch {"                                             + "\r\n" +
        "    returnValue = new " + returnType + "();"           + "\r\n" +
        "}"                                                     + "\r\n" +
        "return returnValue;";
    pMethod.Statements.Add(new CodeSnippetExpression(completeMethod));

//    Here you can look at what the assembled method looks like
//    Console.WriteLine(completeMethod);

    CodeTypeDeclaration pClass = new CodeTypeDeclaration(className);
    pClass.Attributes = MemberAttributes.Public;
    pClass.Members.Add(pMethod);
    CodeNamespace pNamespace = new CodeNamespace(namespaceName);
    pNamespace.Types.Add(pClass);
    for (int i = 0; i < usingList.Length; i++)
    {
        pNamespace.Imports.Add(new CodeNamespaceImport(usingList[i]));
    }

    CodeCompileUnit pUnit = new CodeCompileUnit();
    pUnit.Namespaces.Add(pNamespace);
    CompilerParameters pParams = new CompilerParameters(importList);
    pParams.GenerateInMemory = true;
    CompilerResults pResults = (new CSharpCodeProvider()).CreateCompiler().CompileAssemblyFromDom(pParams, pUnit);

    if ((pResults.Errors != null) && (0 < pResults.Errors.Count))
    {
        foreach (CompilerError pError in pResults.Errors)
        {
            Debug.WriteLine(pError.ToString());
        }
        return null;
    }
    else
    {
        object typeInstance = pResults.CompiledAssembly.CreateInstance(namespaceName + "." + className);
        MethodInfo methodInfo = typeInstance.GetType().GetMethod(methodName);
        return methodInfo.Invoke(typeInstance, new object[] { args });
    }
}

CompilerResults pResults = (new CSharpCodeProvider()).CreateCompiler().CompileAssemblyFromDom(pParams, pUnit);