Visual Basic 6.0 Easy Learning: December 2007

Wednesday, December 19, 2007

How to shows the use these declaration statements for actual variable for following code

Private numval As Integer

Private avgval As Integer, inptval As Variant

Static clcAverage As Single

Dim inptmsg as string

It is best to declare your variables using the Dim or other statements shown earlier, but you also can assign a type to a variable using an implicit declaration. With this type of declaration, a special character is used at the end of the variable name when the variable is first assigned a value.

How to use the variable declarations

Each of the following statements can be used to explicitly declare a variable’s type:

Dim varname [As vartype] [ , varname2 [As vartype2]]

Private varname [As vartype] [ ,varname2 [As vartype2]]

Static varname [As vartype ] [ , varname2 [As vartype]]

Public varname [As vartype] [ , varname2 [As vartype2]]

Dim, Private, Static, and Public are Visual Basic keyword that define how and where the variable can be used. varname and varname2 represent the names of the variables that you want to declare. As indicated in the syntax, you can specify multiple variables in the same statement, as long as you separate the variables by commas.

Vartype and vartype2 represent the type definition of the respective variables. The type definition is a keyword, which tells VB what kind of information will be stored in the variable.

How to use VB6 to create a simple division program

a) The interface of the program, it’s support three type of division.

b) The source code of the division program at the command button.

inpt1 = Text1.Text

inpt2 = Text2.Text

Text3.Text = inpt1 / inpt2

Text4.Text = inpt1 \ inpt2

Text5.Text = inpt1 Mod inpt2

c) The result is like below

How to use different control used to handle different types of data

Control Name	Data Type	Control Property
Label	Text, Numeric, Date	Caption
TextBox	Text, Memo, Numeric, Date	Text
CheckBox	Logical, True/False	Value
PictureBox	Long Binary	Picture
Image	Long Binary	Picture

How to use the special character at the end of a variable name can identify the type of data stored by the variable

The special character at the end of a variable name can identify the type of data stored by the variable.

Variable Type	Character
Integer	%
Long	&
Single	!
Double	#
Currency	@
String	$
Byte	None
Boolean	None
Date	None
Object	None
Variant	None

How to use the type of variables

- Below is the type of variables.

Type	Stores	range of values
Integer	whole numbers	-32768 to 32767
Long	whole numbers	+/- 2 billion
Single	decimal numbers	+/- 1E-45 to 3E38
Double	decimal numbers	+/- 5E-324 to 1.8E308
Currency	number with up to 15 digits left of	+/- 9E14
	the decimal and 4 digit right of the decimal
String	text information	up to 65000 character
Byte	whole numbers	0 to 255
Boolean	logical values	True or False
Date	date and time information	1/1/100 to 12/31/9999
Object	picture and OLE object	N/A
Variant	any of the preceding data type	N/A