Guide to Visual Basic 6

Introduction:

What are you going to learn from this guide?

You are about to learn how to properly code in Visual Basic.
And maybe pick one or two things that you did not know before.
I am assuming that you are able to choose a control from the toolbox
and placed on the form and setting properties.
I've broken the guide into four parts.

Part1 - The basics involving writing good code and formats.

Part 2 - The code base> The visual basic commands.

Part3 - Advanced Visual Basic - Dealing with API and a lot of interesting things.

Part4 - Extra Goodies

Part 1: Basics

An important part of being a good programmer, Visual Basic is good for the use of file names and controls. It may seem like extra work, but in the long run, it will allow you to code faster and allow yourself and others better understand your own code.

A rule that I use for prefixesis to keep the code in lowercase and capitalize the first letter of the name of the control or file.

Prefixes for files:

Project prj =

frm = Form

mod = module

CLS = Class

User usr = control

Prefixes Common Controls

LBL = Control Label

Command Button cmd =

Img = Image control

pic = Image box

TMR = Timer

Shape shp =

chk = Checkbox

LST = Listbox

Textbox txt =

opt = Option (Radiobutton)

hs = horizontal scroll bar

vs = the vertical scroll bar

CBO = combobox

MNU = Menu

SCK = Winsock

Bad names do not use!

Form1

Command1

Timer1

Picture1

Good Names

frmMain

cmdClose

TmrLoop

picView

Prefixes can also be very useful when writing code.

String str =

lng = Long

int = Integer

SNG = Single

bln = Boolean

var = Variant

BadExample:
dim stuff as a string

stuff = InputBox ("Enter your name")

good example:

dim strName as String

strName = InputBox ("Enter your name")

Part 1B. Make the legible part of code 2.

You've already learned how prefixes can help make the code easier and faster.
Now we move on and return comments!

One of the worst things is about finding the code that is not returned and / or any space blank.

Bad example

subProcessNumber (ByRef intNumber as a whole)

= 3 then if intNumber

more

intNumber if = 4 then

End If

End If

End Sub

Good example:

sub ProcessNumber (ByRef intNumber as integer)

If intNumber = 3, then

Other

If intNumber = 4 then

End If

End If
End Sub

When you indent?

Tab is also a time when you start to code in an event or a subroutine.
Then for each if statement, loop, you alsohyphen.

Comments:

Visual Basic Comments begin with 'and can go anywhere you want
They are useful to explain the code for yourself and others.
I really wish VB had comments on multiple lines, as in C + + but it is not so bad.

White Space:

Leaving white space makes the code easier to read and makes it look cleaner

Part 2: The Code

The fun stuff starts now.

The first line in all shapes and forms must be
OptionExplicit

What does Option Explicit do?
Well, it forces you to declare all variables with them otherwise they do all the type of variant.

Sample so you can not do:

for i = 0-100
the next

You have to have before I said
Dim i as byte
for i = 0-100
the next

Variables

What are the variables? They contain data that can change when you run the program

Bytes = 0-255 numbers holds
String = holds the characters or letters as"Hello World! E numbers too 123456789"
Integer = numbers without decimals from -32,768 to 32,767
Long = numbers with no decimal -2147483647 to 2147483647
Single = May contain decimal numbers 32bit
Holds Boolean = True or False

Constants

What are the constants? They argue that the data does not change.
An example would be a constant
Private Const Pi = 3.14

Private / Public / Global

What do you mean private?

Private means that you can only accessin its present form, a module or class.

What public and the global average?

Public means that it can be accessed from any shape, form or class

Static

If you make a static variable that will save its value the next time the sub is running.

If then statements

A line, if then statement

If condition = True then blnSomething = true

Multi-line if then statement
If condition = true then
'Your code goes here

End If

Complex if then elsestatements

If condition = True Then

Other

'Condition = false

End If

If condition = true then

ElseIf contition2 = True Then

End If

Select Case statement:

As the switch statement in C + +
What is it good for?
And 'good for instances when you have a variable and
do not want to have a million, if then statements.

Example

intNumber Dim As Integer

select case intNumber

Case 1:

case 2:

Another case:

endselect

Loops:

For Next loop
Syntax

For step 100 = 0-100

next

Do While

Do Until

Overview Subs and Functions of ByVal and ByRef
By default all parameters are passed by reference in Visual Basic which means they are passing
the memory address and not the value.
Sub Test ()

strReturnValue dim as string

Test2 call (strReturnValue)

msgbox strReturnValue

End Sub
Sub Test2 (as StrRefString)

StrRef = "Hello World"

End Sub

What is a function? A function is a special type of procedure that returns a value, for example,
Sub Main

AddNumbers msgbox (3.4)

End Sub
private function AddNumbers (ByVal intNumber1 as Integer, ByVal intNumber2 As Integer) As Integer

AddNumbers = (+ intNumber1 intNumber2)
End Function

In the above example shows a message box with the result of 7

You can specify how you want to pass a parameterby reference (ByRef)
or by value (ByVal) You want to use pass by value when you are not going to change the parameter.

Sub Example (StrRef ByRef As String, ByVal intNumber As Integer)

End Sub

Some quick reference:

All Visual Basic functions and commands are listed in the object browser.
It looks like a box with things coming out in the toolbar.

Use App.Path instead of hard-coded paths.
App.Path returns the path to yourapplication

You can use app.previstance to detect whether the application is already running.

Part 3: Advanced Visual Basic Information

Section A: Understanding API
Your guide to Visual Basic Api is [http://www.allapi.net]
Once seen allapi.net
Get API Viewer 2004 tons lists VB API
Get Help API API and has many examples of how to use them.

Conversion of API C + + Visual Basic Api
VB= Integers C + + Short
Longs C + + VB = Whole

Section B: Pointers

There is a common myth going around that Visual Basic does not support pointers.
This is not true that they are just hidden.

VarPtr
ObjPtr
StrPtr

AddressOf - Used for finding addresses and procedures

Section C: Understanding VB binary data.

Visual Basic stores a string in the following format
Length As Integer
Text as String

Bytes occupy abytes of data.

Boolean occupies two bytes or 00 00 or FF FF

Integer to take up two bytes.

Long takes four bytes.

Single occupies four bytes.

Double occupies eight bytes.

Section D: Reverse Engineering VB Visual Basic (5 / 6)

For a couple of months this was the area that I worked on.
For Visual Basic 6 exe there are two methods for native compilation or P-code.
P-Code is pretty easy to understand what all the opcodes are known and it is just
question to understand what opcode does what and which connects the imports of the exe.
Natives on the other hand it is difficult is to convert assembly code Visual Basic.
Check out [http://decompiler.theautomaters.com] - Visual Basic Decompiler forum
for more information.

Section E: Build DLL in Visual Basic as a real C + +

By default Visual> Basic DLL with no exports, is only active x dll.
But you can do in Visual Basic if you can intercept the compilation process.
You can make your own c2.exe to intercept the parameters passed to the real c2.exe then pass that
the final information to create a DLL file with the normal real exports.

Section F: Debugging / Decompiling

I like to use Debug.Print advice or use a MsgBox statement to see what's going on in mycode.
excellent tool for debugging a compiled exe - SmartCheck.

Visual Basic Decompiler list:

Semi VB Decompiler - http://www.visualbasiczone.com

VB Parser 1.2

Race

VB Reformer

VBDE

VB Editor

VBREZQ

EXDEC

Section G: Choose the type of compilation.

Visual Basic offers two ways to compile the native application or P-Code

Native-

It's faster

More difficult to Decompile

Yoularger

P-Code

Slower

Easier to Decompiler

Smaller EXE

Part 4: extra extra

Section A: Links!

http://www.pscode.com - best place to search for the Visual Basic.

http://www.vbgamer.com - dealing with Visual Basic Games

[Http: / / decompiler.theautomaters.com] - Visual Basic Decompiler forum

http://www.visualbasiczone.com - my site for VB

http://www.vbcity.com - Excellent communitypeople aware

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