Microsoft Visual C++ .NET Professional Projects - Premier Press

In Chapter 8, you encountered the SaveMyMoney Bank, which had a banking application created to handle the day-to-day activities of the bank. The banking application was created using MFC, and used ODBC for data access. The banking application has been successfully implemented across the many branches of the bank. However, now the management is thinking of re-creating the application as a .NET application, since they see many advantages in completely moving onto the .NET platform. But before migrating to .NET, they intend to create a pilot application that implements only some of the features of the original banking application and verify its performance.

As part of the pilot, they want to implement the login feature and the accounthandling feature of the existing MFC’s Banking application in Managed C++.

Database Schema

In the pilot project, the database for the SaveMyMoneyBankApplication bank comprises two tables:

The AccountDetail table stores details of bank accounts of customers.

The BankLogin table stores the username and passwords of users who are authorized to access the banking application.

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472 Project 3 ADO.NET IN MANAGED C++

values(‘Masine’,’Philip’,’09/09/72’,’Street V Opp. Great Circle’,’Bldg-11, Avenue

2’,’91-20392012’,’mph@pinc.com’,’S’,800,’VA’,0)

go

Creating the BankLogin Table

The BankLogin table is used for storing the username and password of users who are authorized to access the application. The following query creates the Login table and adds a sample value to it:

print ‘Creating table BankLogin’ create table BankLogin

(

UserNm varchar(5) not null,

Pwd varchar(15) not null

)

go

insert BankLogin values(‘S103’,’password’) go

Having created the database structure for the application, you will now create the Windows application for the bank, by using Managed C++.

Creating the Banking Application

To create the banking application using Managed C++, you need to follow these steps:

1.Create a new project by using the Managed C++ Application project template.

2.Design the Login form and implement its business logic.

3.Design the form to manage account details and implement its business logic.

In this section, I examine the steps to accomplish each of the preceding tasks.

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Creating a Project in Managed Extensions

To create a project in Managed Extensions, you use the Managed C++ Application project template provided in Visual Studio .NET. In this section, you create the MCppBankOperations project by using this template.

Follow these steps to create the banking application by using the Managed C++ Application template:

1.Open Visual Studio .NET.

2.Click on the File menu, click on New, and then click on Project. The New Project dialog box will appear.

3.In the New Project dialog box, click on Visual C++ Projects in the Project Types list. The templates available for creating Visual C++ projects will appear in the Templates list.

4.In the Templates list, click on Managed C++ Application and specify the name of the project as MCppBankOperations in the Name text box. The completed New Project dialog box is shown in Figure 14-1.

5.Click on OK.

FIGURE 14-1 The New Project dialog box

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#using “System.Data.dll” #using “System.Xml.dll” #include <tchar.h>

using namespace System;

using namespace System::ComponentModel; using namespace System::Windows::Forms; using namespace System::Drawing;

using namespace System::Data;

using namespace System::Data::SqlClient; using namespace System::Xml;

Next, you need to write the code for creating the LoginForm class, which is derived from the Form class, and renders the login form for the user. The code snippet given below creates the LoginForm class and declares variables with private scope, which will be later used for rendering controls on the form:

__gc class LoginForm: public Form

{

private:

//Variables to store the caption, width, height of the form

String *caption; int width;

int height;

//Variables to render the controls of the form

TextBox *loginid;

TextBox *pwd;

Label *lglabel;

Label *pwdlabel;

Button *submitbutton; Button *cancelbutton; ErrorProvider *error; int totallogincount;

public:

//Constructor

LoginForm()

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Controls->Add(lglabel);

// To add the labels pwdlabel = new Label(); pwdlabel->Text=”Password”;

pwdlabel->Size = Drawing::Size(90, 20);

pwdlabel->Location = Drawing::Point(width/2-90, height - 120); Controls->Add(pwdlabel);

// Code to create the Submit button submitbutton = new Button(); submitbutton->Text = “&Submit”; submitbutton->Size = Drawing::Size(90, 30); submitbutton->TabIndex = 2;

submitbutton->Location = Drawing::Point(width/2-100, height - 70); submitbutton->Click += (new EventHandler(this, &LoginForm::OnSubmitButtonClick));

Controls->Add(submitbutton);

// Code to create the Cancel button cancelbutton = new Button(); cancelbutton->Text = “&Cancel”; cancelbutton->Size = Drawing::Size(90, 30); cancelbutton->TabIndex = 3;

cancelbutton->Location = Drawing::Point(width/2+10, height - 70); cancelbutton->Click += (new EventHandler(this, &LoginForm::OnCancelButtonClick));

Controls->Add(cancelbutton);

//Create the error provider control error=new ErrorProvider(); error->BlinkRate=250;

error->BlinkStyle=ErrorBlinkStyle::BlinkIfDifferentError;

}

After the Login form is displayed, the user will enter his or her login ID and password. This data is validated against the entries in the database. If the login ID or the password does not match, an error is displayed. If the login attempt fails

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//Establishing Connection

//You can use this format if you are connecting with a known user name and //password; however, it is not recommended to store these in the source for //security reasons

// Create the SQL Connection object and pass it the connection string

SqlConnection* sqlconn = new SqlConnection(connectString);

//Open the connection sqlconn->Open();

//Create the SQL Command to store the select query

SqlCommand *sqlCommand = new SqlCommand(query, sqlconn);

//Create a SqlDataReader to enumerate the result of executing the command

//against the database.

SqlDataReader *dataReader = sqlCommand->ExecuteReader();

//Find out if there was a record existing with the given user name and password

//if yes, then increase the count in the variable numrows.

int numrows = 0;

while (dataReader->Read()) // Always call Read before accessing data.

{

numrows = numrows + 1;

}

//This part checks if any rows were selected –validating the user name and

//password entered

if(numrows == 0) //the record doesn’t exist

{

MessageBox::Show(“Invalid login name or password. Please try again.”); loginid->Text=””;

pwd->Text=””; loginid->Focus();

//To check the number of login attempts made totallogincount = totallogincount + 1;