A Visual Basic 6 Programmer’s Toolkit

324 Pages·2000·11.289 MB·English

by  Hank Marquis, Eric A. Smith (auth.)

A Visual Basic
6
Programmer's Toolkit
Hank Marquis and Eric A. Smith
APress Media, LLC
A Visual Basic 6 Programmer's Toolkit
Hank Marquis and Eric A. Smith
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Library of Congress Control Number: 00-13357 4
ISBN 978-3-540-78081-6 ISBN 978-1-4302-5125-5 (eBook)
DOI 10.1007/978-1-4302-5125-5
10 9 8 7 6 54 3 2 1
Trademarked names may appear in this book. Rather than use a trademark symbol
with every occurrence of a trademarked name, we use the names only in an editorial
fashion and to the benefit of the trademark owner, with no intention of infringement
of the trademark.
Copy Editor: TSI Graphics
Production: TSI Graphics
Indexer: Carla Johnson
Cover Design: Derek Yee Design
The information in this boak is distributed an an ·~ ls" basis, withaut warranty.
Althaugh every precautian has been taken in the preparatian af this wark, neither
the authar nar Apress shall have any liability ta any persan ar entity with respect ta
any lass ar darnage caused ar alleged ta be caused directly ar indirectly by the
infarmatian cantained in this wark.
HANK MARQUIS
This book is dedicated to my wife Nur
and my children Adriana and Rolfe.
ERICSMITH
To my wife, ]odi
Brief Contents
Acknowledgments ................................ xiii
About the Author ................................. xv
Chapter 1: Arrays and Array Manipulation ............ 1
Chapter 2: Strings and String Handling .............. 23
Chapter 3: Fun with Numbers, Numeric
Processing and Logic .............................. 41
Chapter 4: Working with Dates and Times ............ 59
Chapter 5: Data Structures: Versatile
Veh1des for Data Storage .......................... 69
Chapter 6: Windows Files, Directories and Drives ...... 89
Chapter 7: Persistence: Remernhering What
You Can't Afford to Forget ........................ 115
Chapter 8: Localization: The Art of Talking
Like a Native .................................... 127
Chapter 9: Working with Networks ................ 141
Chapter 10: Reliable and Flexible Data Validation ..... 161
Chapter 11: Working with the Operating System ...... 183
Chapter 12: Windows Help Systems-From the Inside .. 195
Chapter 13: Multiple Document Interface Forms ...... 201
Chapter 14: Database Programming ................ 229
Chapter 15: Active Data Objects ................... 249
Chapter 16: Objects, Objects and More Objects ....... 269
Chapter 17: WebCiasses: A New Way to
Program for the Web ............................ 289
Index .......................................... 313
V
Detailed Contents
Acknowledgments xiii
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
About the Author xv
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1: Arrays and Array Manipulation 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
(REATING AND USING ARRAYS IN VISUAL BASIC o o o o o 1
0 0 0 0 0 0 0 0 0 0 0 0 0
Sorting Arrays 4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
WORKING WITH SORTED ARRAYS o o o o o o 10
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Finding an Element with a Specific Value in a Sorted Array 1 0
0 0 0 0 0
Inserting an Element into a Sorted Array 11
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Deleting an Element from a Sorted Array 12
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
WORKING WITH DATA IN AN ARRAY 13
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Finding Maximum and Minimum Values in an Array Range 14
0 0 0 0
Array Arithmetic 15
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
More on Array Arithmetic 1 7
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Copying a Range from One Array to Another 1 8
0 0 0 0 0 0 0 0 0 0 0 0 0 0
Persisting Array Data 1 9
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
PERFORMANCE HINTS o 20
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2: Strings and String Handling 23
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
WHAT ISA STRING? o o o o 23
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Examining Strings 24
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
ParsingStrings 30
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Changing Strings 34
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
3: Fun with Numbers, Numeric Processing, and Logic 41
0 0
BINARY ANALYSIS OF NUMBERS o o o o o o o o o o o o o o o o 41
0 0 0 0 0 0 0 0 0 0 0 0
Negative Numbers 42
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Binary Digits in Visual Basic Numbers 43
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
HEXADECIMAL HOCUS POCUS o o o o o o o 45
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
MORE ON BIT FLAGS o o o o 4 7
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bytes from Words 49
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Words from Longs 50
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
BINARY-(ODED DECIMAL o o o o o o o 51
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Next Steps for Warking with BCD Strings 52
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
METRICS 52
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
SPELLING ÜUT NUMBERSo 53
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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4: Working with Datesand Times ................... 59
DATE ARITHMETIC .................................... 60
Leap Years ..................................... 60
Calculating Days . . . . . . . . . . . . . . . . . . . . . . ........... 61
FORMATTING DATES ................................... 62
JULIAN DATES ....................................... 64
Next Steps ..................................... 66
WORKING WITH TIME .................................. 66
SUMMARY ......................................... 68
5: Oata Structures: Versatile Vehicles for
Oata Storage .................................... 69
DATA STRUCTURES IN VISUAL BASIC ......................... 69
Arrays ........................................ 69
User-Defined TYPes ............................... 69
Enumerated TYPes . . . . . . . . . . . . . . . . . . . . . . . ......... 71
Classes ....................................... 72
Key-Item Pairs .................................. 76
HASHING ......................................... 80
Creating the Data Structures Needed for Hashing ........... 80
Hashing the Data . . . . . . . . . . . . .................... 82
Searching the Hash Table . . . . . . ..................... 84
Testing the Hashing Solution ......................... 86
6: Windows Files, Directories, and Drives ............ 89
FILES, DIRECTORIES, AND DRIVES ........................... 89
WINDOWS APPLICATION PROGRAMMING INTERFACE ............... 90
FILES ......................................... 91
File Existence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1
Finding a File ................................... 92
Getting a Unique Temporary Filename .................. 93
Changing a File's Date and Time Stamp .................. 95
Retrieving a Short Filename ......................... 99
Recycling Instead of Deleting ......................... 99
WINDOWS DIREGORIES ................................ 101
Windows System Directory . . . . . . . . . . . . . . . . . . . . . . . . . 1 02
Windows Directory .............................. 1 02
Temporary File Directory . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 03
WINDOWS DISK DRIVES ................................ 10 4
Determining the Number of Drives . . . . . . . . . . . . . . . . . . . . 1 04
Detecting Drive TYPe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 06
DriveSpace ................................... 107
viii
Drives Larger Than 2 GB . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 0
Drive Serial Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Reading and Writing the Drive Name . . . . . . . . . . . . . . . . . . 113
7: Persistence: Remembering What You Can't
Afford to Forget ................................ 115
PERSISTENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
INI FILES ........................................ 116
Reading a String Value from an INI File . . . . . . . . . . . . . . . . . 116
Reading a Numeric Value from an INI File . . . . . . . . . . . . . . . 118
Writing INI File Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 9
Deleting INI Entries .............................. 120
THE WINDOWS REGISTRY ............................... 120
Reading from and Writing to the Registry . . . . . . . . . . . . . . . 12 1
8: Localization: The Art of Talking Like a Native ..... 127
LOCALIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7
ACTIVEX (OMPONENTS THAT ADAPT ........................ 127
From Visual Basic to Self-Localizing ActiveX Controls ....... 128
Creating Resource Files ........................... 130
Creating Self-Localizing ActiveX DLLs and Documents ...... 131
Implementing Language DLLs . . . . . . . . . . . . . . . . . . . . . . . 133
Setting Default Fonts ............................. 136
Handling Other Languages ......................... 140
9: Working with Networks ........................ 141
ACCESSING A NETWORK ............................... 141
Determining Whether a Network Is Present . . . . . . . . . . . . . . 141
Reading the Username ............................ 142
Reading the Computer Name ........................ 143
Setting the Computer Name . . . . . . . . . . . . . . . . . . . . . . . . 143
Finding the Next Free Network Drive . . . . . . . . . . . . . . . . . . . 144
(ONNECTING TO A NETWORK RESOURCE ..................... 145
Disconnecting from a Network Resource ................ 146
Network Dialogs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7
THE INTERNET EXPLORER API: ACCESS TO THE
INTERNET WITHOUT A ßROWSER .......................... 149
Installing the Run-Time Files ........................ ISO
Opening an Internet Channel . . . . . . . . . . . . . . . . . . . . . . . . 151
Connecting to the Internet Server . . . . . . . . . . . . . . . . . . . . . 152
Connecting to the Data Sink . . . . . . . . . . . . . . . . . . . . . . . . 152
Posting Form Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Reading the Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Closing All the Handles ............................ 156
Putting the Pieces Together: A Complete Data-Source Program . 156
ix
10: Reliable and Flexible Data Validation ........... 161
VALIDATION OF NUMERIC DATA ........................... 161
IsNumeric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
1)'peName . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Var1)'pe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
VALIDATION OF DATES ................................. 164
IsDate ....................................... 165
VALIDATION OF TEXT ENTRIES ............................ 166
Text Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 6
Text Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7
VALIDATING ÜTHER TYPES OF DATA ......................... 167
PUTTING IT ALL TaGETHER .............................. 168
BuHding the Data-Entry Form ....................... 168
Setting Essential Properlies ......................... 169
Enforcing Character Validation . . . . . . . . . . . . . . . . . . . . . . 1 71
Reformatting Input Data . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 3
Credit Card Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 6
Wrapping Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 1
11: Working with the Operating System ............ 183
RETRIEVING SYSTEM INFORMATION ......................... 183
DETERMINING THE AMOUNT OF MEMORY .................... 183
DETERMINING HOW WINDOWS STARTED ..................... 185
GETTING AND SETTING ENVIRONMENT VARIABLES ............... 186
Getting an Environment Variable . . . . . . . . . . . . . . . . . . . . . 18 7
Setting an Environment Variable . . . . . . . . . . . . . . . . . . . . . 18 7
Deleting an Environment Variable .................... 188
SHUTTING DOWN AND RESTARTING WINDOWS ................. 188
Shutting Down Windows .......................... 189
Restarting Windows .............................. 189
RETRIEVING HARDWARE INFORMATION ...................... 189
Determining the CPU 1)'pe ......................... 189
Determining the Number of CPUs . . . . . . . . . . . . . . . . . . . . . 19 1
Determining CPU Performance Capabilities . . . . . . . . . . . . . . 1 91
RETRIEVING THE FLAVOR OF WINDOWS AND THE
OPERATING SYSTEM VERSION ............................ 192
Identifying Windows 95/98 ......................... 193
Identifying Windows NT ........................... 193
Identifying the Operating System Version ............... 193
12: Windows Help Systems-From the Inside ......... 195
WINHELP ........................................ 195
DISPLAYING A HELP PAGE ............................... 196
(LOSING A HELP WINDOW .............................. 198
(ONTEXT-SENSITIVE HELP .............................. 198
X
SHOWING A SPECIFIC HELP PAGE .......................... 199
DISPLAYING HELP IN APOP-UP WINDOW .................... 200
SEARCHING HELP .................................... 200
MAKING SURE YOUR HELP FILE IS THE ÜNE THATS VISIBLE .......... 202
DISPLAYING THE HELP WINDOW WHERE YOU WANT .............. 202
PUTTING IT ALL TOGETHER .............................. 204
13: Multiple Oocument Interface Forms ............. 207
MOl FORM ßASICS ................................... 207
SHARING SYSTEM RESGURCES ............................ 209
Sharing in the Real World . . . . . . . . . . . . . . . . . . . . . . . . . . 2 12
MANAGING MENUS .................................. 215
Shared Menu Items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 16
Semishared Menu Items ........................... 220
Custom Menu Items .............................. 224
14: Oatabase Programming ....................... 229
DATABASE FEATURES IN VISUAL BASIC ....................... 229
OLE DB Support ................................ 229
Active Data Objects (ADO) ......................... 230
The Data Environment ............................ 230
The ADO Data Control ............................ 230
Enhanced Data Binding ........................... 230
The Query and Database Designer .................... 230
The Data Report Designer .......................... 231
Data Sources .................................. 231
The Data View Window ........................... 231
The DataRepeater Control .......................... 231
Data Form Wizard Enhancements .................... 231
The Data Object Wizard ........................... 232
ADO-Aware Data Controls ......................... 232
USING THE DATA ENVIRONMENT DESIGNER ................... 232
Creating the Data Environment ...................... 232
Adding a Query ................................. 234
Binding a Data Grid to the Data Environment ............. 23 7
Binding a Record Viewer to the Data Environment ......... 238
Binding a Data Report to the Data Environment ........... 240
USING THE 0ATALIST AND DATA(OMBO (ONTROLS .............. 242
ßUILDING A DATABASE ANALYZER ......................... 244
15: Active Oata Objects .......................... 249
MICROSOFT'S UNIVERSAL DATA ACCESS STRATEGY ............... 249
More on OLE DB ................................ 249
ODBC ....................................... 250
Remote Data Service ............................. 250
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