visual basic 5-6 course part 1

8/9/2019 Visual Basic 5-6 Course Part 1

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Visual Basic 5Programming - 1A Specialised Training Course


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Visual Basic Book 1 Mark Collins 1999 Page 1

Contents

INTRODUCTION ........................................................ ........................................................... 2

What is Visual Basic? ..................................................... ................................................. 2

Why Visual Basic? .......................................................... ................................................. 2

How is Visual Basic so Effective?....................................................... ............................. 3

Is Visual Basic Object Oriented?........................................................ ............................. 3

What are Objects?................................................. ........................................................... 3So where does Event Driven Code fit in? .................................................. .................... 4

Isnt Basic old-fashioned? ........................................................ ....................................... 4

WINDOWS TERMINOLOGY ....................................................... ....................................... 5

AWINDOW ..................................................... ........................................................... .......... 5

INFORMATION BOXES ........................................................... ................................................. 7

Dialog Box .................................................. ........................................................... .......... 7

Message box........ ............................................................ ................................................. 7

CONTROLS ........................................................ ........................................................... .......... 8

Buttons ........................................................ ........................................................... .......... 8

Text Boxes ................................................... ........................................................... .......... 8

Option Buttons ...................................................... ........................................................... 8

Check Boxes.......................................................... ........................................................... 8 List Boxes.................................................... ........................................................... .......... 8

Pictures / Images......................................... ........................................................... .......... 8

A LOOK AT THE CONTROLS................................................... ................................................. 9

OTHER FEATURES....................................................... ........................................................... 9

THE VISUAL BASIC IDE .................................................... ............................................... 10

WHATS ON SCREEN................................................... ......................................................... 10

VISUAL BASIC APPLICATION WINDOW..................................................... ........................... 11

Title Bar ...................................................... ........................................................... ........ 11

Menu Bar .................................................... ........................................................... ........ 11

The Toolbar....................................... ........................................................... .................. 11

THE FORM WINDOW................................................... ......................................................... 12

THE TOOLBOX .................................................. ........................................................... ........ 12PROJECT WINDOW...................................................... ......................................................... 13

PROPERTIES WINDOW........................................................... ............................................... 13

EDIT WINDOW................................................... ........................................................... ........ 13

THE PROJECT .................................................. ........................................................... ........ 14

Forms.......................................................... ........................................................... ........ 14

Code Modules ....................................................... ......................................................... 14

Class Modules..... ............................................................ ............................................... 15

Custom Controls ................................................... ......................................................... 15

Resource Files / Binary Data.......................................... ............................................... 15

PLANNING YOUR PROJECT ON PAPER AND OTHER GOOD PRACTICES.................................... 15

MAKE AN EXE FILE.................................................... ......................................................... 15

EXERCISES ....................................................... ........................................................... ........ 16


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Introduction

What is Visual Basic?Visual Basic is a programming tool for developing Applications.

There are several versions available now, in this course we will

use Version 5 Professional Edition, the 32-bit version. Much of

this course is applicable to previous editions, any significant

differences will be mentioned.

Version differences will be highlighted in sections likethis one.

One of the myths surrounding Visual Basic is that you can

develop powerful applications without any programming. It is

indeed possible to create very simple applications with a minimum

knowledge of the Basic programming language, but in order to

create anything substantial a developer needs to utilise more

advanced concepts of Visual Basic programming. We will develop

these during the course.

Why Visual Basic?When you choose to develop a Windows application there are

various alternatives available including...

use a Database application (e.g. Access or Paradox).

use a proper programming language such as C, C++ orPascal.

use Visual Basic.

There are advantages and disadvantages with each of these

approaches. With a Database you are locked into using a

Database format, which may limit the scope of your project. With

one of the other languages mentioned you certainly have a lot

more scope and control, but they have a slower learning curve and

development time is far longer than Visual Basic.

Visual Basic allows us to develop fast, powerful applications with

less complexity than say C++, and with the capability to utiliseMicrosoft Access database files (if we want). It also allows

increased integration with other applications (e.g. MS Office)

through OLE.


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How is Visual Basic so Effective?Visual Basic is run in a GraphicalIDE (Integrated Development

Environment). Many of the controls are mouse controlled and you

are creating your applications interface directly on screen.

It is designed to run under Windows(v3.x, 95 & NT) developing

Windows applications. All the different standard controls are

implemented such as Buttons, Combo Boxes, Menu Bars and

Toolbars. As these have all been provided as standard Objects

we just need to know how to control them, we dont need to re-

invent the proverbial wheel each time.

During development you can safely test your project by using

Visual Basic as an interpreter. However, when your project is

finished you can then create an Executable file (or files) to

distribute and use. There are various runtime files which your

executable needs, but you do not need Visual Basic installed to

run a Visual Basic Application.

Is Visual Basic Object Oriented?With Version 5 the answer is definitely Yes although many OO

purists may disagree. At the initial level you do not need to be an

OOPS Guru to use it as the objects have been provided for you

to implement and control as you require. You can also befairly

sure that the Objects provided are fully tested and free of bugs.

What are Objects?An object is a programming term to describe a special kind of data

item. In addition to containing the data the object also knows howto manipulate that data. Each different process that the object can

perform on its data is known as aMethod. The technical term

used to describe this combination of Data and associated processes

isEncapsulation.

Other OO languages have additional concepts calledInheritance

andPolymorphism. These are not applicable in Visual Basic,

they are complex and unnecessary for most work.

An additional concept of Objects is that the only way to

manipulate the data is to us one of the associated methods. Code

outside the object can not directly manipulate the data, but it canpass a message to the object activating one of the methods.

In Visual Basic the primary objects available areforms and

controls. Aform is simply a Window of one type or another. A

controlis an object we place on aform, such as abutton or atext

box.

Visual Basic 5 also allows you to create your ownclass of object

usingclass modules.

Each Visual Basic Object has a set ofproperties. These may

contain the actual data we wish to process or some attribute of the

object such as its name or the colour of the background. Much ofthe actual programming involves manipulating these properties.


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So where does Event Driven Code fit in?Each object also has an associated set of event procedures. For

example abutton will probably contain a Click procedure which

contains the code to run when the button is clicked with the

mouse.

This differs greatly from the standard type of program, a

proceduralprogram. A procedural program runs through a

sequence of commands, that may branch through various routes,

but generally leading you through the program from beginning to

end.

An event driven program reacts to...

your prompting an event (e.g. clicking a button, selectingfrom a list, using a scroll bar, starting the application, etc.)

a system event (e.g. a timer)

from a program instruction causing an event another application exchanging information.

You, the developer, choose which events your program should

react to and what processing to perform at each event. This is

where the actual BASIC coding comes in.

Isnt Basic old-fashioned?A decade ago Basic was still used extensively to produce what

were then powerful applications. Programmers however started to

move across to more structured languages as their demands

increased. Basic developed to meet these new demands but was

not taken seriously as a proper language. Microsoft persisted,

bundling it in the form ofGWBasic and then QBasic with MS-

DOS. It wasnt until the latter years however that Microsoft

brought it back to the fore. They wanted a language that a

hobbyist programmer could use to develop serious applications in

a new Windows based graphical IDE without too steep a learning

curve.

Their strategy has now developed to replace the various Macro

languages in their Windows applications (Word, Excel etc) with a

standard Visual Basic Macro language, known as Visual Basic for

Applications - effectively a library of objects for use with VisualBasic. The latest versions are seeing this strategy come to

fruition.


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Windows Terminology

Before we start Exploring Visual Basic itself it is important thatwe develop a standard terminology to describe its various

features. Microsoft have a standard name for each item which we

will use throughout this course. Unfortunately as Microsoft are an

American company many names have an American spelling

which we will use (grudgingly).

A window

To avoid confusion I will refer throughout to Windows (3.x, 95/98

or NT), the software package, with a capital W and in italics. An

individual window will be in normal text.

A window is a rectangular frame that can contain anything from

a complete application to a group of icons to a picture document.

Your work happens inside these windows. You can have several

of these windows open simultaneously, each running a different

application. By switching thefocus from window to window you

can move between them, effectively running multiple applications.

A window containing a running application is anapplication

window. An application window may contain severalchild

windows. These are otherwise known asdocument windows. In

Windows adocument can be more than a text file. It can be a

picture, a list of filenames, a group of icons (like within ProgramManager) or another type of document.

Child Window within Parent Window

Child

Window


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Information BoxesThese are often confused with windows but perform specific input

and/or output tasks. The two main instances to understand are the

dialog box andmessage box.

Dialog BoxAdialog box prompts the user to supply information needed by

the program to continue with the application. There are standard

common dialog boxes used in many Windows applications for

example for file-specification.

A dialog box will usually consist of some input controls (text

boxes, list boxes etc.) and at least two buttons. An OK button is

used to accept the input and proceed. A Cancel button is used to

back-out of the dialog box without accepting any of the input.

Message boxA message box appears when the program or the system needs to

inform you about a specific situation. This may be a warning or

error message.

To indicate the message type it is standard practice to include one

of four icons...

Exclamation mark

Question mark

Stop sign

Information sign

There should be at least one button to select depending on the

choices available.


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ControlsAs mentioned previously, controls are objects placed within forms

(i.e. windows or information boxes). As the name suggests these

objects can be manipulated to allow input or output from the

application. Here is the first set of the most common...

ButtonsRespond to a single mouse click. A caption or icon/picture on the

button indicates its use. Buttons generally appear three-

dimensional and sink into the screen when activated.

Text BoxesA text box is an object containing all the functionality to enter

textual or numerical information into your application. This

functionality includes full editing (insertion, deletion etc.).

A text box may besingle-line to enter a single word or number, ormulti-line to enter large blocks of text.

Option ButtonsOtherwise known asRadio-buttons, they appear in groups where

one button only is to be selected. Selecting a new button will

deactivate the previously selected button. If a single button is

required then you should use Check Boxes.

Check BoxesOften confused with option buttons, a check box is a square which

may or may not be selected (on/off, yes/no, true/false). Mayappear in groups, but unlike option buttons any combination of

selected buttons may be allowed.

List BoxesProvides a list from which to choose one or more items.

Depending on the mode chosen you can select single or multiple

items. If the size of the list is too big for the list box then a vertical

scroll bar is added.

There are two basic types, a standard list box and acombo-box .

In the combo-box only a single selected item is usually shown, but

clicking the down arrow button to the right drops a list from which

to select.

Pictures / ImagesThese are graphical controls. A picture control is usually used to

display information although it is possible for them to respond to

mouse clicks etc.


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A look at the ControlsThe following diagram shows some of these controls in use.

Other FeaturesThere are many other features too many to mention at this stage

but that we will cover through the course.

These includeDDE (Dynamic Data Exchange) and OLE (Object

Linking and Embedding) - especially OLE, which allow us to

integrate applications. There is also the Windows API, a body of

over 800 functions that we can use to interact with the Windows

environment. This is advanced stuff, but will allow us eventually

to create powerful applications.

For the most part the complexity involved in developing Windows

applications has been dramatically reduced with Visual Basic as

most of the complex details are dealt with automatically - until we

want to take full control ourselves.


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The Visual Basic IDE

In order to develop our Windows applications in Visual Basic weuse the Visual Basic IDE (Integrated Development Environment).

As a Windows application itself it offers all the benefits of a

graphical interface. Using the mouse and keyboard we can

quickly design and code our applications on it.

Whats on ScreenWhen we start-up Visual Basic, the following windows appear on

screen. We will work through the windows in turn.


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Visual Basic Application WindowThis consists of the...

Title bar

Menu bar

Toolbar

Title BarContains the title Microsoft Visual Basic [mode] where the

mode is either [design], [break] or [run].

Menu Bar

As with many Windows applications you have several ways ofselecting menu options; by using the mouse or keyboard to select

an option, or by using a keyboard shortcut. You should

familiarise yourself with the menu commands, but for now heres

a summary of the important sections...

Menu Activities

File Opening, closing and saving projects.

Printing forms or code.

Creating an EXE file.

Edit Undoing and redoing actions.

Cut / copy / Paste.Find / replace.

View Affects what you see in the Visual Basic IDE.

Insert For adding extra forms / modules etc.

Run Alters depending on which mode you are in, and lets you

switch between mode. Debug stepping here too.

Tools Tools and Options

Add-Ins Particularly the Data-Manager, other extras can be added

Help Used to access Visual Basic Help files. There are several files

on various topics, each of which can be accessed.

The ToolbarThis consists of a set of buttons / icons used as short-cuts for many

of the menu options.


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The Form WindowThis is where we design the windows and dialog boxes that are

going to appear in our application. One way of viewing it is as a

Visual Basic Document. Depending on the design we may place

controls on our form.

The ToolboxThis window contains buttons to access the set of controls that you

select to include in your application. As you add or remove

modules from your default project file or your current project file

the buttons change.

part of the toolbox.

The set of tools shown depends on which version and edition you

have and which custom controls you have enabled through the

Project / Components menu.

To add a control to our form we select the relevant button from thetoolbox and click on the form to place a default size control, or

click and drag on the form to place a control of a specific size.

NB. If you open up a project and you want to a control thats not

on the toolbox then press ctrl+T to load up the tabbed components

dialogue box. During the course various controls will be needed

and you have to use this dialogue box to select the required

controls to add to the general toolbar, so that the controls can be

used in your project.


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Project WindowThis window lists the various forms and modules included in this

project. You can access the various components from here as well

as adding and deleting them.

Properties WindowAs you manipulate forms and the controls on those forms this

window shows the properties of the currently selected object(s).

You can change a property at design-time by selecting the

property and editing its value.

Edit windowThis is where you can edit the code associated with an object.

Double clicking an object brings up the code edit window.


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The Project

In Visual Basic a project can be regarded as all the parts requiredto create our application. The details of these are contained in a

Project file with the extension *.VBP ( *.MAK in VB3) Yourapplication will consist of several parts including...

Forms

Code Modules

Class Modules (VB4 and VB5)

Custom controls

Binary Data / Resources

Each of these apart from the Custom controls are files that youwill create. For a single project it is good practice to store them in

a single sub-directory with the same name as your project file.

What are the different components of a Project for?

FormsThese are the workspaces on which we will design our windows

and dialogue boxes. An application may consist of several forms

which can be loaded, unloaded, shown and hidden by the code.

Each form is stored in its own *.FRM file and contains adescription of the forms appearance, including the controls placed

on it. The form also contains the code for procedures andvariables associated with the form itself and the individual

controls.

Code ModulesIn an application with several forms it is likely that there will be

code not specifically attached to a single form. This code

(variables, constants & procedures) is stored in a Code Module

and is available to any form. A Code module has a file extension

of*.BAS


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Class ModulesA new addition since VB4, class modules differ from code

modules in that it is more object-oriented - a single class of object

is defined in a Class Module. They are stored in *.CLS files

Custom ControlsThese are additional controls to the standard set that can be added

to your toolbox. The Professional Edition has many more of these

that the Standard Edition. It is also possible to obtain third-party

controls to add yourself. A custom control has the file extension

*.OCX or the older *.VBX. Active X controls can be regarded asmore complex custom controls.

Resource Files / Binary DataThese files store specialised data required when an icon or picture

is included at design time. In VB3 they were *.FRX, in VB4 they

are *.RES files and in VB5 & 6 they are *.FRX.

Planning your Project on Paper and other goodpractices

Initially we will be dealing with simple applications that are

relatively small and simple to create. As you start to develop

larger applications keeping track of your project becomes difficult

so spending time planning and designing on paper becomes

important. You should prepare what controls you are likely to

need; the processes to be performed and the variables and

constants that are required to support the processing. Attemptingto develop on the fly will soon present you with problems.

Visual Basic allows a very flexible approach to development. The

ability to click the Run button and test what you have at any time,

without a lengthy compile process, enables you to test-as-you-go.

This cycle of creating or modifying an object (including properties

and code) followed by a test followed by a rethink and repeating

the cycle can continue as your project develops stage by stage

until you have a finished product. This you convert to an EXE file

and use outside Visual Basic.

Thisprototyping method should not be allowed to take over from

careful and considered planning. It is all too easy to return to a

project after a weekend away and to have completely lost track of

what you were doing. Your code will also develop in a haphazard

way with inconsistencies, duplication or redundancy creeping in.

Make an EXE fileThis prepares your project for use independent of Visual Basic.

All the necessary code is compiled into files that can then run

independently. Your application is now ready to use, distribute or

sell as necessary.


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Exercises

Create a sub-directory C:\PROJECTS\WELCOME to save the project of

the same name in exercise 2.

Exercise 1.Run a Sample Project.

This exercise uses an existing project to familiarise you with the Visual Basic

IDE.

1. Either click on the Open project button on the tool bar or select

File/Open project from the menu.

Locate On drive C:\ PROGRAM FILES \DEVSTUDIO \PGUIDE

\SAMPLES \CONTROLS directory. In the file selection box you

should see CONTROLS.VBP. Select this project (double click the

name, or highlight the name and click OK).

2. The Project window will appear with one entry. Expand this by

clicking on the plus symbol. Note the contents identifying the type of

files included. How many forms are there?

Has the Toolbox changed? Can you explain why (hint - *.OCX files)?

3. Use the Run button on the toolbar to execute the project. Note how the

Visual Basic Application window remains, but the mode is now [Run].

A window will appear with a single menu called Options. Select each

option in turn, trying out various controls on each.

4. When you have investigated enough, exit the application. How many

ways are there to exit this application? (You should findat least three)

5. You should now be back in [design] mode. Use the Project window to

view each form in turn. Can you identify the control types on each

form?

6. Return to the MAIN form in [design] mode. The EXIT command

button has some code to perform when it is clicked. Double-click it in

design mode to see that code. It is not vital that you understand the

construct of the code yet.

7. If you are exiting Visual Basic now or starting a new project you neednot save any changes you may have made to this project.


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Exercise 2Writing a simple application

If you are not in Visual Basic load it as previously. If you are select File/New

Project from the menu (do not save any changes to the sample application

from exercise 1)1. You should have a blank form window with the title bar form 1.

Make sure that this is the active window. Note the various defaults in

the properties window. Make the following changes in the property

window...

Property Old value New value

Name Form1 frmWelcome

Caption Form1 Welcome

2. Adjust the size of the form until it is about a quarter of the size of your

screen. Do you notice properties changing as you do this?3. Add a simple label control. Select the label control (the toolbox button

with a capital A) and click-and-drag a rectangle in the middle of your

form. Make sure that this control is highlighted and change the

following properties. (To change the autosize property between True

and False you can either use the drop-box selector or double click the

property)


Autosize False True

Caption Label1 Welcomeyourname

4. Reposition the label and resize the window if you like. When you are

happy with your layout Run your application (a grand title at this stage

I know, but from small acorns...).

5. There is not a lot we can do at this stage except play around with the

window, so stop the application.

6. Save the project.

- Select File/Save Project from the menu or click the Save button on

the toolbar.

- You are first asked to select the name and location to store any forms

or modules. The form we renamed in part 2 of this exercise alreadyhas a suitable name (frmWELCO.FRM) . We now need to select the

E:\PROJECTS\WELCOME directory we created earlier and click OK.

- You are now asked to save the project file. PROJECT1.VBP is notthat informative, so rename it WELCOME.VBP. The location is

the F:\PROJECTS\WELCOME directory from before so click OK.

Note: The general routines described above for creating and saving new

projects will be the same except for the filenames for future projects.


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Exercise 3Improving the Welcome application.

If you are continuing on directly from exercise 2 the Welcome project should

be active in Visual Basic, if not then load it from disk.1. Amend the label in the frmWelcome form as follows...


Caption Welcomeyourname Enter your name:

2. Add a text box below the label (identify and select the correct toolbox

button, the click and drag a rectangle). Make it approximately the

same size as the label. Change the following properties for this

control...

Property Old value New valueName Text1 txtName

Text Text1 clear the text

3. Add a command button below the text box, again about the same

width but about three times as tall. Give this button the following

properties...


Name Command1 cmdOK

Caption Command1 OK

4. Now for some code. Double-click the button to bring up the code

window. Amend the text for this event to appear as follows...

Sub cmdOK_Click ()

MsgBox "Welcome " & txtName.Text

End Sub

Although VB will allow you to use a + instead of an & to

concatenate strings the ampersand is safer.

5. Run and use the application. Note how we already have quite a lot

going on, but we have only written a single line of code. Return to

[design] mode.


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6. Add a second button to the right of the OK button of the same size.

Give it the following properties...


Name Command1 cmdQuit

Caption Command1 QUIT

7. We will use this button to exit our application. Amend the

cmdQuit_Click code as follows...

Sub cmdQuit_Click ()

End

End Sub

8. Test your application again. If you are happy with it then save your

project again (the filenames shouldnt need changing).

9. Make an executable file so that we can run it outside of Visual Basic.- Select File/Make EXE file...

- Select C:\ as the location for WELCOME.EXE

10. Quit Visual Basic (saving any changes if not done so already).

Load Welcome.exe as an icon in Program manager and run it.

Supplementary Tasks

Run through the windows tutorial to familiarise yourself with theterminology etc. (Accessible from the Help menu of Program Manager

or run Start/Help from Windows 95/98)

Try running and investigating some of the other sample applications.

visual basic 5-6 course part 1

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