Essential Visual Basic 6.0 fast

215 Pages·2000·12.31 MB·English

by  John Cowell BSc (Hons)

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John Cowell
Essential
Visual Basic 6.0
fast
'Springer
John Cowell, BSc (Hons), MPhil., PhD.
Department of Computer and Information Sciences, De Montfort University,
Kents Hill Campus, Hammerwood Gate, Kents Hill,
Milton Keynes MK7 6HP, UK
ISBN-13: 978-1-85233-207-5
British Library Cataloguing in Publication Data
Cowell, John, 1957-
Essential Visual Basic 6.0 fast
1. Visual Basic (Computer program language) 2. Visual
programming (Computer science)
I.Titie II.Visual Basic 6.0 fast
005.1'33
ISBN-13: 978-1-85233-207-5 e-ISBN-13: 978-1-4471-3417-6
DOl: 10.1007/978-1-4471-3417-6
Library of Congress Cataloging-in-Publication Data
A catalog record for this book is available from the Library of Congress
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as
permitted under the Copyright, Designs and Patents Act 1988, this publication may only be repro
duced, stored or transmitted, in any form or by any means, with the prior permission in writing of
the publishers, or in the case of repro graphic reproduction in accordance with the terms of licences
issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms
should be sent to the publishers.
© Springer-Verlag London Limited 2000
Microsoft, MS, Visual Basic, Windows, Windows 95 and Windows 98 are trademarks of Microsoft
Corporation Ltd.
Java and Hot Java are trademarks of Sun Microsystems Corporation Ltd.
Pentium is a trademark of Intel Corporation Ltd.
The use of registered names, trademarks etc. in this publication does not imply, even in the absence of
a specific statement, that such names are exempt from the relevant laws and regulations and therefore
free for general use.
The publisher makes no representation, express or implied, with regard to the accuracy of the infor
mation contained in this book and cannot accept any legal responsibility or liability for any errors or
omissions that may be made.
Typesetting: Camera-ready by author
34/3830-543210 Printed on acid-free paper SPIN 10741535
Contents
1 WHY USE VISUAL BASIC 6.0? .......................................................... 1
Introduction ............................................................................................. 1
Visual Basic 6.0 editions ......................................................................... 1
What computer do you need to run Visual Basic 6.0? ............................ 2
Why change to version 6.0? .................................................................... 2
Is this book for you? ................................................................................ 3
How to use this book ............................................................................... 3
Conventions ............................................................................................. 4
2 THE VISUAL BASIC IDE .................................................................... 5
Introduction ............................................................................................. 5
Running Visual Basic .............................................................................. 5
The Project Explorer ................................................................................ 8
The design form ....................................................................................... 9
The Toolbox .......................................................................................... 10
Adding ActiveX controls ....................................................................... 11
The Properties window .......................................................................... 12
The Form Layout window ..................................................................... 13
The menu bar and the tool bar ............................................................... 13
Finding elements of the IDE .................................................................. 14
Getting Help .......................................................................................... 14
3 THE INTRINSIC CONTROLS .......................................................... 15
Introduction ........................................................................................... 15
Adding controls to a window ................................................................ 15
Selecting, moving and resizing controls ................................................ 16
The Label control .................................................................................. 17
Changing the properties of a control ..................................................... 17
Common properties ............................................................................... 18
Properties of the Label control .............................................................. 19
Running an application .......................................................................... 20
The TextBox controL ............................................................................. 20
Passwords .............................................................................................. 21
The PictureBox and Image controL ...................................................... 21
The CheckBox, OptionButton and Frame controls ............................... 22
The CommandButton control ................................................................ 24
v
vi Contents
4 HANDLING EVENTS ......................................................................... 25
Introduction ........................................................................................... 25
Displaying pictures ................................................................................ 25
Creating a new project .......................................................................... 26
Creating the user interface .................................................................... 26
Adding a new form ................................................................................ 27
Adding a new control to a project... ...................................................... 28
Naming the controls .............................................................................. 30
Handling events ..................................................................................... 30
The Form Load event handler ............................................................... 30
The Quick Info facility .......................................................................... 32
The OptionButton event handlers ......................................................... 33
The CommandButton event handlers .................................................... 35
A quick way of making event procedures ............................................. 36
Saving your application ........................................................................ 36
Making an executable file ..................................................................... 37
5 CONTROLLING PROGRAM FLOW .............................................. 38
Introduction ........................................................................................... 38
Adding comments ................................................................................. 38
Spreading a statement over multiple lines ............................................ 39
More than one statement to a line ......................................................... 39
The ComboBox and Image controls ..................................................... 39
The ComboBox control. ........................................................................ 40
Creating an application ......................................................................... 41
Using the ComboBox control ............................................................... 41
The With statement ............................................................................... 42
Using the If. . Then .. Else statement ........................................................ 43
Using the Select Case statement ........................................................... 44
Closing an application ........................................................................... 46
The comparison operators ..................................................................... 46
Looping ................................................................................................. 47
The While .. Wend statement .................................................................. 47
The Do .. While statement. ...................................................................... 48
The Do .. Until statement ........................................................................ 49
The For .. Next statement ........................................................................ 49
6 VARIABLES AND OPERAT ORS ..................................................... 51
Introduction ........................................................................................... 51
Naming conventions ............................................................................. 51
Variable types ........................................................................................ 52
Declaring variables ................................................................................ 52
Static variables ...................................................................................... 53
Variable scope ....................................................................................... 53
Declaring constants ............................................................................... 54
Contents vii
The Boolean data type ........................................................................... 54
Data types representing integers ............................................................ 55
Data types representing floating point numbers .................................... 55
The Date data type ................................................................................. 55
The Object data type .............................................................................. 56
The String data type ............................................................................... 57
The Variant data type ............................................................................ 57
The range of data types .......................................................................... 58
Converting between data types .............................................................. 59
Rounding and truncating integers .......................................................... 60
Arithmetic operators .............................................................................. 60
Arrays .................................................................................................... 60
Declaring arrays ..................................................................................... 60
Changing array dimensions ................................................................... 61
The Erase statement ............................................................................... 62
User-defined data types ........................................................................ 62
7 USING MENUS .................................................................................... 64
Introduction ........................................................................................... 64
The Menu Editor. ................................................................................... 64
Enabling and disabling controls ............................................................ 67
Pop--up menus ....................................................................................... 68
Menu events ........................................................................................... 70
8 FORMS AND DIALOGS .....•.•.••••.•.•.••.•.••.•.•.••••.••••.•.••••.•..................... 71
Introduction ........................................................................................... 71
The MsgBox statement and function ..................................................... 71
The button parameter ............................................................................. 73
The helpfile and context parameters ..................................................... 75
Using returned values ............................................................................ 75
The InputBox function .......................................................................... 76
The CommonDialog control .................................................................. 77
The File Open dialog ............................................................................. 78
The Color dialog .................................................................................... 81
The Font dialog ...................................................................................... 82
The Print dialog ..................................................................................... 83
Creating custom dialogs ........................................................................ 85
Showing and hiding dialogs .................................................................. 87
9 INTRINSIC AND ACTIVEX CONTROLS ...................................... 88
Introduction " ......................................................................................... 88
The Timer control .................................................................................. 88
The ListBox control ............................................................................... 89
The Slider control .................................................................................. 92
viii Contents
The RichTextBox control. ..................................................................... 94
The MonthView control ........................................................................ 96
The DateTimePicker control ................................................................. 97
The MSFlexGrid control ....................................................................... 99
Using the MSFlexGrid controL ......................................................... 100
The UpDown control .......................................................................... 105
The ProgressBar controL .................................................................... 107
10 MOUSE AND KEYBOARD EVENTS .......................................... 110
Introduction ......................................................................................... 110
The KeyPress event. ............................................................................ 110
The KeyUp and KeyDown events ...................................................... 111
Using bit masks ................................................................................... 112
Using the KeyUp and KeyDown events ............................................. 112
Mouse events ....................................................................................... 113
The MouseMove event ........................................................................ 114
The MouseDown and MouseUp events .............................................. 115
Dragging and dropping ....................................................................... 116
The Drag method ................................................................................. 116
Dropping the control in the correct position ....................................... 117
The DragIcon method ......................................................................... 118
The DragOver event ............................................................................ 118
11 FUNCTIONS AND PROCEDURES .............................................. 12 0
Introduction ......................................................................................... 120
The Password application ................................................................... 120
Creating a procedure ........................................................................... 123
Passing parameters .............................................................................. 125
Creating functions ............................................................................... 127
Call by reference and call by value ..................................................... 127
Optional parameters ............................................................................ 129
Using a start-up procedure ................................................................. 130
12 OBJECT-ORIENTED PROGRAMMING ................................... 133
Introduction ......................................................................................... 133
Classes and objects .............................................................................. 133
Creating objects at run-time ............................................................... 135
User-defined classes ........................................................................... 136
Creating forms at run-time ................................................................. 138
13 DEBUGGING ••..••..••..•.•.•.••.•••••...•.•.•.••.•.•.••.•....••.•.••.•••..•..•.•..•.•.••••.••. 140
Introduction ......................................................................................... 140
What is debugging? ............................................................................ 140
Contents ix
The Debug tool bar .............................................................................. 141
Running and pausing applications ....................................................... 141
Breakpoints .......................................................................................... 142
Stepping through an application .......................................................... 143
The Run to Cursor command .............................................................. 144
Continuing and stopping ...................................................................... 144
Displaying the value of variables ........................................................ 144
The Quick Watch window ................................................................... 145
The Locals window ............................................................................. 145
The Immediate window ....................................................................... 146
Watch expressions ............................................................................... 147
The Call Stack window ....................................................................... 148
Conditional compilation ...................................................................... 149
14 THE VISUAL DATA MANAGER ................................................. 151
Introduction ......................................................................................... 151
The flight booking system ................................................................... 151
Creating a new database ...................................................................... 152
Creating the Passenger table ................................................................ 153
Add data to the Passenger table ........................................................... 157
Creating the Flight table ...................................................................... 158
One-to-many relationships ................................................................. 159
Running SQL statements ..................................................................... 160
Recordsets ............................................................................................ 161
The Data Form Designer ..................................................................... 162
Running the application ....................................................................... 164
Data-aware controls ............................................................................ 164
15 THE DATA FORM WIZARD ........................................................ 166
Introduction ......................................................................................... 166
Running the Data Form Wizard .......................................................... 166
Choosing the database ......................................................................... 167
Choosing the format ............................................................................ 167
Setting the master record source ......................................................... 169
Setting the detail record source ........................................................... 169
Connecting the data sources ................................................................ 170
Selecting the controls .......................................................................... 171
The completed application .................................................................. 172
How flexible is the Data Form Wizard? ............................................. 17 3
16 ADO AND DATA-BOUND CONTROLS ..................................... 174
Introduction ......................................................................................... 174
ActiveX data objects ............................................................................ 174
Data controls ........................................................................................ 175
x Contents
ODBC providers .................................................................................. 175
Creating a DSN ................................................................................... 176
Using the ADO data controL ............................................................. 178
Properties of the ADO data control... .................................................. 181
ADO data control events ..................................................................... 182
17 ADO DATA CONTROL EVENTS ................................................ 183
Introduction ......................................................................................... 183
The Recordset object. .......................................................................... 183
Methods of the Recordset object... ...................................................... 186
Events of the ADO data control... ....................................................... 188
18 ACTIVEX DOCUMENTS .............................................................. 190
Introduction......................................................................................... 190
Why use ActiveX documents? ............................................................ 190
Creating an ActiveX document... ........................................................ 191
The Shape control ............................................................................... 192
Creating an animation ......................................................................... 193
Adding forms and menus to ActiveX documents ............................... 195
ActiveX containers .............................................................................. 196
The ActiveX document Viewport ....................................................... 197
The ActiveX document Migration Wizard ......................................... 198
INDEX .................................................................................................... 201