Introduction to Microsoft Visual Basic

Microsoft Visual Basic Fundamentals

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Microsoft Visual Basic is a programming environment used to create graphical user interface (GUI) applications for the Microsoft Windows family of operating systems. It usually ships either by itself or as part of Microsoft Visual Studio. To follow these lessons, you must have installed either Microsoft Visual Basic 2008 Express Edition, Microsoft Visual Basic 2008 Professional, or Microsoft Visual Studio 2008 (Professional). To get Microsoft Visual Basic 2008 Express Edition, you can download it free from the Microsoft web site. After downloading it, you can install it.

From now on, unless specified otherwise, we will use the expressions "Microsoft Visual Basic" or "Visual Basic" to refer to Microsoft Visual Basic 2008.

After installing it, to use Microsoft Visual Basic, you must launch. To launch Microsoft Visual Basic 2008 Express Edition, you can click Start -> (All) Programs -> Microsoft Visual Basic 2008 Expression Edition. If you are using Microsoft Visual Studio 2008 Professional, to start it, on the task bar, you can click Start -> (All) Programs -> Microsoft Visual Studio 2008 -> Microsoft Visual Studio 2008:

Microsoft Visual Basic presents itself as a series of tools used to assist you in creating computer programs. As a normal Windows application, it starts on top with a menu and some toolbars. It is also equipped with various windows, considered as tools, you will be using. Most of these tools are available or are functional only if you have primarily created or opened a project.

• To launch Microsoft Visual Basic:
  If are using Microsoft Visual Basic 2008 Express Edition, on the taskbar, click Start -> (All) Programs -> Microsoft Visual Basic 2008 Express Edition
  If you are using Microsoft Visual Studio 2008, on the task bar, click Start -> (All) Programs -> Microsoft Visual Studio 2008 -> Microsoft Visual Studio 2008

A toolbar is an object made of buttons. These buttons provide the same features you would get from the (main) menu, only faster. Under the main menu, the IDE is equipped with the Standard toolbar. By default, the Standard toolbar is positioned under the main menu but you can position it anywhere else on the IDE. To move a toolbar, position the mouse on the dotted line on its left section. The mouse pointer will change into a cross:

Then click and drag away from that position:

In the same way, you can position the toolbar anywhere on the screen. You can also attach or "dock" it to one of the four sides of the IDE. When a toolbar is not docked to one side of the IDE, it is said to float. When a toolbar is floating, you can resize it by dragging one of its borders. If a toolbar is floating, to put it back to its previous position, you can double-click its title bar.

By default, when you start Microsoft Visual Studio, it is equipped with one toolbar: Standard. To get more toolbars, on the main menu, you can click View -> Toolbars and click the toolbar of your choice. You can also right-click any available toolbar or the main menu. This displays a list of all the available toolbars. Those that are currently opened have a check mark next to them.

A toolbar is equipped with buttons that could be unfamiliar. Just looking at one is not obvious. To know what a button is used for, you can position the mouse on top of it. A tool tip will come up and display for a few seconds.

In our lessons, each button on any toolbar will be named after its tool tip. This means that, if a tool tip displays "Hungry", its button will be called the Hungry button. If a tool tip displays "Save All", its button will be called the Save All button. If you are asked to click a button, position your mouse on different buttons until one displays the referred to name.

Some buttons present an arrow on their right side. This arrow represents a menu. Here is an example:

Like the menu, the toolbars can be customized. To customize the Standard toolbar by adding buttons to it, you can right-click anything on the main menu or the toolbar and click Customize... On the Customize dialog box, you can click the Commands tab. In the Categories list, you can click a category, such as Debug. In the Commands list, you can click and drag an item, position it somewhere in the Standard toolbar, and release the mouse. Here is an example:

When you have finished, you can click the Close button on the Customize dialog box

The Start Page is the first wide area that appears when Microsoft Visual Studio comes up. The section displays a title as Recent Projects. At any time, to display the Start Page:

• You can click its tab on the left side just under the Standard toolbar
• On the main menu, you can click View -> Other Windows -> Start Page
• On the main menu, you can click Windows -> Start Page

If you have just installed Microsoft Visual Studio or have not previously opened a project, the Recent Projects section would be empty. Here is an example:

Once you start creating and using projects, they display in the Recent Projects section by their names.

The middle section allows you to check new articles from Microsoft and partners directly from Visual Studio 2008 through an Internet connection.

When you start or open a project, Microsoft Visual Studio 2008 makes some windows available. These are the most regularly used windows. If you think that one of them is not regularly used in your types of assignments, you can remove it from the screen. To hide a window:

• You can click its Close button
• You can click its title bar and click Hide

All of the windows you can use are listed in the View menu. Therefore, if a window is not displaying, you can click View on the main menu and click a window of your choice.

When creating your applications, you will use a set of windows that each accomplishes a specific purpose. Some windows are represented with an icon but hide the rest of the body. To display such a window, you can position the mouse on it. This would expand the window:

If you expand a window, it would display a title bar with two buttons. One is called Auto Hide and the other is the classic Close button:

If you expand a window but find out you don't need at that position, you can just move the mouse away from it. The window would return to its previous state. Based on this functionality, if you are working with a window and move the mouse away from it, it would retract. If you need it again, you would have to reopen it using the same technique. If you are going to work with a certain window for a while, you can keep it open even if you move the mouse away. To do this, you can click the Auto Hide button. If clicked, the Auto Hide button changes from pointing left to pointing down .

By default, Visual Studio 2008 installs some windows to the left and some others to the right of the screen. You can change this arrangement if you want. To do this, expand a window, then click its title bar and start dragging. When you do this, the screen would display 5 buttons: one to each side and one in the middle:

To position a window on one side of the screen, drag it title bar to one of the four buttons on the sides.

You can dock a window only if it is dockable. To make sure that a window is dockable, you can right-click its title bar and click Dockable:

If you don't want the window to be dockable, you can right-click its title bar and click Floating.

Most of the windows you will use are positioned on one side of the screen. If you want, you can have a window that stays on top of other window but cannot  be "glued" to one side. Such a window is said to float. To float a window, drag its title bar and release it somewhere in the middle of the screen but not on one of the previously mentioned button because, while dragging, if you release the mouse on one of the buttons, and if the window is dockable, it would assume the position of where you released the mouse.

If you don't want a window to be dockable and you only want it to float, right-click its title bar and click Floating.

Instead of accessing a window from one side of the screen or from its sharing an area with another window, you can make it display a tab. To do this, drag its title bar and release the mouse when its gets to the middle button that displays some tabs:

When a window is tabbed, you cannot drag its tab to position it on one side of the screen. If you want to remove it from its tabbing position, first right-click its tab and click either Floating or Dockable.

You can make two or more windows share one side of the screen or to share an area. To do this, drag its title bar to the window whose area you want to share, then position the mouse on the middle button and release it.

To create a computer program, also called an application, you create a series of files and group them in an ensemble called a project. This contains various modules, files, assemblies (or libraries), and resource files.

A typical application consists of more than one module and can even be as complex as you want. To make it faster and a little easier to graphically create an application, you would need a good functioning environment like Microsoft Visual Basic. Using it, you can create a new project or you can open an existing one.

To create a Visual Basic project, you can display the New Project dialog box. To open the New Project dialog box:

• On the Start Page, on the right side of Project, click Create...
• If you are using Microsoft Visual Basic 2008 Express Edition, on the main menu, you can click File -> New Project... If you are using Microsoft Visual Basic 2008 Professional, on the main menu, you can click File -> New -> Project...
• On the Standard toolbar, you can click the New Project button
• You can press Ctrl + Shift + N

In the New Project dialog box, select Visual Basic Projects, select the type of project, give it a name, specify its directory, and click OK.

1. On the main menu, click File -> New Project or File -> New -> Project...
2. In the Templates section, click Console Application
3. In the Name edit box, type Exercise1
    
   
4. Accept the name in the  Location text box and click OK. This creates a new project

The instructions created for a Visual Basic project are written in plain English in a language easily recognizable to the human eye. After creating the file(s) of a project, you would compile the project to get an executable that becomes ready to be distributed to your users.

To compile and execute a project in one step, on the main menu, you can click Debug -> Start Without Debugging. Although there are other techniques or details in compiling (or debugging) and executing a project, for now, this is the only technique we will use until further notice.

1. To execute the application, on the main menu, click Build -> Build Exercise1

2. To execute the application, on the Standard toolbar, click the Start Debugging button

As opposed to creating a new project, you can open a project that either you or someone else created. To open an existing project:

• On the Start Page, on the right side of Project, click Open...
• If you are using Microsoft Visual Basic 2008 Express Edition, on the main menu, you can click File -> Open Project... If you are using Microsoft Visual Basic 2008 Professional, on the main menu, you can click File -> Open -> Project...
• You can press Ctrl + Shift + O

This action would display the Open Project dialog box. This allows you to select a project and open it.

With Microsoft Visual Studio, you can add one project to another, instead of starting one anew. To add a project to an existing one:

• On the main menu, you can click File -> Add -> New Project...
• If more than one project exist already, in the Solution Explorer, you can right-click the top node (the name of the first project), position the mouse on Add, and click New Project...

Any of these actions would display the Add New Project dialog box. You can then select the type of project in the Templates list, give a name to the project, and click OK. In the same way, you can add as many projects as you judge necessary to your solution. When a solution possesses more than one project, the first node in the Solution Explorer becomes Solution 'ProjectName' (X Projects). The ProjectName represents the name of the first project and X represents the current number of projects.

When you are using more than one project in the same solution, one of the projects must be set as the startup. The project that is set as the startup has its name in bold characters in the Solution Explorer. You can change and use any project of your choice as the startup. To do this, in the Solution Explorer, you can right-click the desired project and click Set As StartUp Project.

When a solution possesses more than one project, you can build any project of your choice and ignore the others. To build one particular project, you can right-click it in the Solution Explorer and click Build.

Microsoft Visual Basic is a programming environment that allows you to create various types of applications. In our lessons, we will mostly create graphical applications, also called Windows applications or Windows Forms applications. 

A Windows application primarily appears as a rectangular object that occupies a portion of the screen. This type of object is under the management of the operating system, Microsoft Windows. Based on the functionality of Microsoft Windows, for an application to become useful, it must be opened. An application must have an entry point. On a C/C++ application, this entry point is a function called main. On a Win32 application, this entry point is a function called WinMain. In the Visual Basic language, this entry point is a function named Main.

1. To create a new application, on the main menu, click File -> New Project or File -> New -> Project...
2. In the Project Types list, expand Visual Basic and click Windows.
   In the Templates section, click Empty Project
3. In the Name edit box, type Exercise2 and click OK
4. On the main menu, click Project -> Add New Item...
5. In the Templates list, click Module
6. Change the Name to Exercise
    
   
7. Click Add
8. Change the contents of the file as follows:
    

   Module Exercise Function Main() As Integer Return 0 End Function End Module

Although you can directly create a graphical application when starting your project, if you had created a console application, you can still easily transform it into a Forms application:

• The most required action consists of changing some characteristics of the project. To take care of this, on the main menu, you can click Project -> ProjectName Properties... and then change the value of the Output Type combo box to Windows Application
• Before or after setting the Output Type to Windows Application, you can create a form 

1. On the main menu, click Project -> Exercise2 Properties...
2. On the left side, make sure Application is selected.
   In the right section, click the arrow of the Output Type combo box and select Windows Application
    
   
3. Save and close the window

Windows Forms is a technique of creating computer applications based on the common language runtime (CLR). It offers a series of objects called Windows Controls or simply, controls. These controls are already created in the .NET Framework through various classes. Application programming consists of taking advantage of these controls and customizing them for a particular application. To exploit these controls and other features of the .NET Framework, there are various types of applications you can create, including graphical applications (Windows Application), web-based applications (ASP.NET Web Application), console applications (Console Application), etc.

The objects used in a Windows application are stored in libraries also called assemblies. As normal libraries, these assemblies have the extension .dll (which stands for dynamic link library). In order to use one of these objects, you must know the name of the assembly in which it is stored. Then you must add a reference to that assembly in your application.

To add a reference to an assembly, on the main menu, you can click Project -> Add Reference... You can also right-click the name of the project in the Solution Explorer and click Add Reference... Any of these actions would display the Add Reference dialog box from where you can click the reference, click Select and click OK. If you don't see the reference you are looking for, you can locate it on another drive or directory using the Browse button.

There are two broad categories of objects used in a Windows Forms application: the forms and the controls. A form is the most fundamental object used on an application. It is a rectangular object that uses part of the computer desktop to represent an application. A form is based on the Form class that is defined in the System.Windows.Forms namespace created in the System.Windows.Forms.dll assembly. Every GUI application you will create starts with a form. There are various techniques you can use to get a form in your application:

• You can programmatically and manually create a form
• You can inherit a form from the Form class
• You can create a form based on another form that either you or someone else created already, etc.

The primary means of getting a form into an application consists of deriving one from the Form class.

1. To add a reference to the assembly in which the Form class is defined, on the main menu, click Project -> Add Reference...
2. In the Add Reference dialog box, click the .NET tab if necessary and scroll down in the list
3. Click System
4. Press and hold Ctrl
5. Click System.Windows.Forms
    
   
6. Click OK
7. To inherit a form from the Form class, change the file as follows:
    

   Imports System.Windows.Forms Module Exercise Public Class Starter Inherits Form End Class Function Main() As Integer Return 0 End Function End Module

8. Save the file

The form is the object that gives presence to an application. Once you have created the (primary) form of your application, you can get it ready to display on the screen. This is taken care of by the Application class equipped to start an application, process its messages or other related issues, and stop the application.

The Application class provides the overloaded Run() method that can be used to start a program. One of the versions of this method takes a form as argument. This form must be the first, main or primary form of your application; it will be the first to display when the application comes up.

1. To prepare the application for starting, change the Main() method as follows:
    

   Imports System.Windows.Forms Module Exercise Public Class Starter Inherits Form End Class Function Main() As Integer 'Instantiate an Program object Dim frmStart As Starter ' Allocate memory for the object, using the new operator frmStart = New Starter ' Call the Run() static method of the Application ' and pass it the instance of the class to display Application.Run(frmStart) Return 0 End Function End Module

2. Test the application
    
   
3. Close it by clicking its system Close button and return to your programming environment

Besides the windows and functionalities we reviewed earlier, when you work on a project, there are other features that become available.

The Server Explorer is an accessory that allows you to access SQL Server databases without using the physical server and without opening Microsoft SQL Server:

The items of this window display in a tree. To expand a node, you can click its + button. To collapse it, click its - button.

The Solution Explorer is a window that displays the file names and other items used in your project:

The items of this window display in a tree. To expand a node, you can click its + button. To collapse it, click its - button. To explore an item, you can double-click it. The result depends on the item you double-clicked.

The Solution Explorer can be used to create a new class, a new folder, or a reference. To perform any of these operations, you can right-click a folder node such as the name of the project, position the mouse on Add and select the desired operation. You can also perform any of these operations from the Project category of the main menu.

Besides adding new items to the project, you can also use the Solution Explorer to build the project or change its properties. If you add one or more other project(s) to the current one, one of the projects must be set as the default. That project would be the first to come up when the user opens the application. By default, the first project created is set as the default. If you have more than one project, to set the default, right-click the name of the desired project in Solution Explorer and click Set As StartUp Project.

The Solution Explorer also you to rename or delete some of the items that belong to your project.

1. To start a new project, on the main menu, click File -> New -> Project...
2. In the Templates list, click Empty Project and change the Name to Exercise3
3. Click OK
4. On the main menu, click Project -> Exercise3 Properties...
5. In the left frame, make sure Application is selected.
   In the right frame, click the arrow of the Output Type combo box and select Windows Application
6. If the Solution Explorer is not visible, on the main menu, click View -> Solution Explorer.
   In the Solution Explorer, right-click Exercise3 and click Add Windows Form...
7. In the Templates list, make sure Windows Form is selected.
   Set the Name to Exercise and click Add

The Class View displays the various classes used by your project, including their ancestry. The items of the Class View an organized as a tree list with the name of the project on top:

The Class View shares some of its functionality with the Solution Explorer. This means that you can use it to build a project or to add new class.

While the Solution Explorer displays the items that are currently being used by your project, the Class View allows you to explore the classes used in your applications, including their dependencies. For example, sometimes you will be using a control of the of the .NET Framework and you may wonder from what class that control is derived. The Class View, rather than the Solution Explorer, can quickly provide this information. To find it out, expand the class by clicking its + button.

1. If the Class View is not visible, on the main menu, click View -> Class View.
   In the Class View, expand the Exercise3 node if necessary.
   Right-click the name of the project Exercise3 -> Add -> Class...
2. In the Templates list, make sure Class is selected. Change the Name to Central and click Add

There are two main ways you will manipulate an object of your application, visually or using code. In future sections, we will explore details of visually designing a control. Code of an application is ASCII text-based, written in plain English and readable to human eyes. For an application, you can use any text editor to write your code but one of Visual Studio's main strengths is the code editor. It is very intuitive.

The Code Editor is a window specially designed for code writing.

Although all languages of the Visual Studio programming environment share the Code Editor, once you have started a type of application, the Code Editor is adapted to the language you are using. Its parser (a program used internally to analyze your code) behaves according to the language of your choice. The features and behaviors of the Code Editor are also different, depending on your language.

The Code Editor is divided in 4 sections:

1. Change the file as follows:
    

   Imports System.Windows.Forms Public Class Central Public Shared Function main() As Integer Application.Run(New Exercise) Return 0 End Function End Class

2. Execute the application to see the new form
3. To create a new class, on the main menu, click Project -> Add Class...
4. Set the Name to Circle and click Add

The top section of the Code Editor displays tabs of property pages. Each tab represents a file. To add a new file to the project, on the main menu, you can click

• File -> New -> File...
• Project -> Add New Item...

Once in the Add New Item dialog box, in the Templates section, click the type of file you want to create, type a name in the Name text box, and press Enter. After the file has been created, it is represented by a tab in the top section of the Code Editor. In the same way, you can add as many files as you judge them necessary. To access a tab:

• You can click its name in the Tabs Bar
• On the main menu, you can click Window and click the name of the desired tab

By default, the tabs display in the order their files were created or added to the project, from left to right. If you don't like that arrangement, click and drag its tab either left or right beyond the next tab

1. To create a new class, on the main menu, click Project -> Add Class...
2. Set the Name to Square and click Add
3. To create a new class, on the main menu, click Project -> Add Class...
4. Set the Name to Triangle  and click Add
5. To access the Circle tab, on the main menu, click Window -> Circle.vb
6. Change the file as follows:
    

   Public Class Circle Private rad As Double Public Property Radius() As Double Get Return rad End Get Set(ByVal value As Double) rad = value End Set End Property Public ReadOnly Property Area() As Double Get Return rad * rad * Math.PI End Get End Property End Class Public Class Sphere Inherits Circle Public Overloads ReadOnly Property Area() As Double Get Return 4 * Radius * Radius * Math.PI End Get End Property End Class Public Class Cylinder Inherits Circle Private hgt As Double Public Property Height() As Double Get Return hgt End Get Set(ByVal value As Double) hgt = value End Set End Property End Class

7. To access another tab, in tabs section, click Triangle.vb
8. Change the file as follows:
    

   Public Class Triangle Private bas As Double Private hgt As Double Public Property Base() As Double Get Return bas End Get Set(ByVal value As Double) bas = value End Set End Property Public Property Height() As Double Get Return hgt End Get Set(ByVal value As Double) hgt = value End Set End Property End Class Public Class Kite End Class

9. Save all

The top-left section of the Code Editor displays a combo box named Class Name. As its name indicates, this combo box holds a list of the classes ( and structures) that are created in the current file. You can display the list if you click the arrow of the combo box:

Each item of the Class Name combo box displays the name of its type associated with its parent as implemented in the code.

1. Click the Circle tab
2. In the Class Name combo box, select Circle

The top-right section of the Code Editor displays a combo box named Members. The Members combo box holds a list of the members of classes. The content of the Members combo box depends on the item that is currently selected in the Class Name combo box. This means that, before accessing the members of a particular class, you must first select that class in the Class Name combo box. Then, when you click the arrow of the Method Name combo box, the members of only that class display:

If you select an item from the Method Name combo box, the Code Editor jumps to that members and positions the cursor to the left of the member.

1. In the Method Name combo box, select Area
2. Press the up arrow key and add a Diameter property as follows:
    

   Public Class Circle Private rad As Double Public Property Radius() As Double Get Return rad End Get Set(ByVal value As Double) rad = value End Set End Property Public ReadOnly Property Diameter() Get Return rad * 2 End Get End Property Public ReadOnly Property Area() As Double Get Return rad * rad * Math.PI End Get End Property End Class . . . No Change

3. Save all

Code is written in a wide area with a white background. This is the area you use the keyboard to insert code with common readable characters. The Code Editor uses some colors to differentiate categories of words or lines of text. The colors used are highly customizable. To change the colors, on the main menu, you can click Tools -> Options... In the Options dialog box, in the Environment section, click Fonts and Colors. To set the color of a category, in the Display Items section, click the category. In the Item Foreground combo box, select the desired color. If you want the words of the category to have a colored background, click the arrow of the Item Background combo box and select one:

In both cases, the combo boxes display a fixed list of colors. If you want more colors, you can click a Custom button to display the Color dialog box that allows you to "create" a color.