Visual Basic 6.0

Palitha Baddegama.Divisional Computer Resource Centre

Hingurakgoda

Visual basic 6.0Visual basic 6.0

Palitha Baddegama , Computer Resource Centre, Hingurakgoda

Form Window

Title barMenu Bar

Tool BarT

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ox

Code Window

Project Window

Property Window

Layout Window

(IDE)Integrated Development

Environment


New Project Dialog Box


Control Description

Pointer Provides a way to move and resize the controls form

PictureBox Displays icons/bitmaps and metafiles. It displays text or acts as a visual container for other controls.

TextBox Used to display message and enter text.

Frame Serves as a visual and functional container for controls

CommandButton Used to carry out the specified action when the user chooses it.

CheckBox Displays a True/False or Yes/No option.

OptionButton Option Button control which is a part of an option group allows the user to select only one option even it displays multiple choices.

ListBox Displays a list of items from which a user can select one.

ComboBox Contains a Textbox and a List Box. This allows the user to select an item from the dropdown List Box, or to type in a selection in the Textbox.

HScrollBar and VScrollBar

These controls allow the user to select a value within the specified range of values

Timer Executes the timer events at specified intervals of time

DriveListBox Displays the valid disk drives and allows the user to selectone of them.

DirListBox Allows the user to select the directories and paths, which are displayed.

FileListBox Displays a set of files from which a user can select thedesired one.

Shape Used to add shape (rectangle, square or circle) to a Form

Line Used to draw straight line to the Form

Image used to display images such as icons, bitmaps and metafiles.

But less capability than the Picture Box

Data Enables the use to connect to an existing database anddisplay information from it.

OLE Used to link or embed an object, display and manipulate data from other windows based applications.

Label Displays a text that the user cannot modify or interact with.


View CodeView ObjectToggle FoldersProject NameForms FolderForm & modules


8

Name PropertyName Property

Must begin with a letterCan contain letters, numbers, and the

underscore character onlyMust not contain punctuation characters or

spaces (!,~,`,@,#,$,%,^,&,*,(,),-,=,+,|,\,/,>,<, ,,; ,:)

Must not exceed 40 characters


Hungarian NotationHungarian NotationUse the three-character IDs shown in

Figure 1-10

Object First three Characters Ex:

Form frm frmAddtion

Command Button cmd cmdStart

Label lbl lblEnd

Text Box txt txtFirst

Menu mnu mnuExit

Check box chk chkChoice

Combo box cmb cmbFont

Figure 1-10


StatementsProcedures

◦Event Procedures◦Sub Procedures◦General Procedures◦Functional Procedures

Comments◦Using single quotation (‘)◦REM

Visual Basic's 6 Most Common Programming Statements

Statement type Examples

Declarations - define the name, type and attributes of all program variables

Dim Num as Integer ' declares a variable "Num" to be an IntegerDim vals(5) as Double ' declares an array of 5 Doubles named "vals"

Assignment - set values for the variables

Num = Num/10 ' after the assignment Num is set to 1/10th of its former valueHiString = "Hello " + "World" ' value of HiString is set to "Hello World"

Conditionals - do operations depending on the value of one or more variables

if Num > 0 then Num = Num * 2 ' Basic logic building blockSelect Case .... End Case 'Case block simplifies GUI programming

Iterations - control looping for repeated operations

for i = 1 to 5 'For-loop counts through a precise number of stepswhile ( val(i) > val(imin) ) 'While loops as long as condition remains True

Subroutines - calls on functions and subroutines

Private Sub Form_Load() 'A subroutine does not return a valuePrivate Function Digit() ' A function returns a value

Special statements - used to implement unique features

Set MyObject = Your Object 'Set statement assigns object referencesPrint #FileNum, MyObject.Text 'I/O statements like Print, Input Line


Operator Mathematical function Example

^ Exponential 2^4=16

* Multiplication 4*3=12, (5*6))2=60

/ Division 12/4=3

ModModulus(return the remainder from an

integer division)

15 Mod 4=3 255

mod 10=5

\Integer Division(discards the decimal

places)19\4=4

+ or & String concatenation"Visual"&"Basic"="Visu

al Basic"

Arithmetic Operators


Operator Meaning

= Equal to

> More than

< Less Than

>= More than and equal

<= Less than and equal

<> Not Equal to

Conditional Operators


Operator Meaning

And Both sides must be true

or One side or other must be true

Xor One side or other must be true but not both

Not Negates truth

Logical Operators


Variable Names

The following are the rules when naming the variables in Visual Basic

• It must be less than 255 characters • No spacing is allowed • It must not begin with a number • Period is not permitted • Reserved Word not allowed Ex. Sub, Private, End

Variable and Data Types


Data TypesData Types

NumericStringDateBooleanObjectVariant

o Integero Floating

pointo Currencyo Byte

Integer Long Single Double


Type Storage Range of ValuesByte 1 byte 0 to 255

Integer 2 bytes -32,768 to 32,767

Long 4 bytes -2,147,483,648 to 2,147,483,648

Single 4 bytes -3.402823E+38 to -1.401298E-45 for negative values 1.401298E-45 to 3.402823E+38 for positive values.

Double 8 bytes

-1.79769313486232e+308 to -4.94065645841247E-324 for negative values 4.94065645841247E-324 to 1.79769313486232e+308 for positive values.

Currency 8 bytes -922,337,203,685,477.5808 to 922,337,203,685,477.5807

Decimal 12 bytes +/- 79,228,162,514,264,337,593,543,950,335 if no decimal is use +/- 7.9228162514264337593543950335 (28 decimal places).

Numeric Data Types


Data Type Storage Range

String(fixed length) Length of string 1 to 65,400 characters

String(variable length) Length + 10 bytes 0 to 2 billion characters

Date 8 bytesJanuary 1, 100 to December 31, 9999

Boolean 2 bytes True or FalseObject 4 bytes Any embedded object

Variant(numeric) 16 bytesAny value as large as Double

Variant(text) Length+22 bytesSame as variable-length string

Nonnumeric Data Types


There are three levels of scope: project-level (also called "global" or "application" scope; the variable is accessible to all procedures in all modules of the project)module-level (the variable is accessible to all procedures in the module in which it is declared)local-level (the variable is accessible only to the procedure in which it is declared)

Variable ScopeVariable Scope

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Variable ScopeVariable Scope

Form1 Form2 Dim Y as Integer Dim Z as Integer

Sub procedure 1 ()Dim A as Double....End Sub

Sub procedure 2 ()Static B as Double....End Sub

Sub procedure 3 ()Dim C as Double....End Sub

Module1Public X as Integer


MsgBox ( ) FunctionA=MsgBox(Prompt, Style Value, Title)

Example:

A=MsgBox( "Click OK to Proceed", 1, "Startup Menu") A=Msgbox("Click OK to Proceed". vbOkCancel,"Startup Menu")


Button Layout Value Short Description

vbOKonly 0 Displays the OK button.

vbOKCancel 1 Displays the ok and cancel button.

vbAbortRetryIgnore 2 Displays the Abort , Retry , Ignore

vbYesNoCancel 3 Displays Yes , No and Cancel button

vbYesNo 4 Displays the Yes / No button

vbRetryCancel 5 Displays the retry and Cancel buttons

Style Values


Value Named Constant Button Clicked

1 vbOk Ok button

2 vbCancel Cancel button

3 vbAbort Abort button

4 vbRetry Retry button

5 vbIgnore Ignore button

6 vbYes Yes button

7 vbNo No button

Return Values and Command Buttons


testmsg = MsgBox("Click to test", 1, "Test message")

testMsg2 = MsgBox("Click to Test", vbYesNoCancel + vbExclamation, "Test Message")


Value Named Constant Icon

16 vbCritical

32 vbQuestion

48 vbExclamation

64 vbInformation

The Icons displayed in the message box are here


InputBox( ) Function A=InputBox(Prompt, Title, default_text, x-position, y-position)

B= InputBox("What is your message?", "Message Entry Form", "Enter your message here", 500, 700)


The numeric functions

a) Int Int(2.4)=2, Int(4.8)=4, Int(-4.6)= -5, Int(0.032)=0 and so on.

b) Sqr Sqr(4)=2, Sqr(9)=3 and etc.c) Abs Abs(-8) = 8 and Abs(8)= 8.d) Exp Exp(1)=e1 = 2.7182818284590e) Fix and Int Fix(-6.34)= -6 while Int(-6.34)=-7 f) Round Round (7.2567, 2) =7.26g) Log Log 10= 2.302585


Len (“welcome to VB tutorial”) = 22Right ("Visual Basic", 4) = asicLeft ("Visual Basic", 4) = VisuLtrim (" Visual Basic")= Visual basicRtrim ("Visual Basic ") = Visual basicTrim (" Visual Basic ") = Visual basicMid ("Visual Basic", 3, 6) = sual BInstr (1, "Visual Basic"," Basic")=8Chr (65)=A, Chr (122)=z, Chr (37)=% ,Asc (“B")=66, Asc(“&")=38


Format Syntax Result

Format(Now,"m/d/yy") 10/02/09

Format(Now,"dddd,mmmm,dd,yyyy") Friday,October 02, 2009

Format(Now,"d-mmm") 02-Oct

Format(Now,"mmmm-yyyy") October -2009

Format(Now,"hh:mm AM/PM") 09:36 AM

Format(Now,"h:mm:ss a/p") 09:40 a

Format(Now,"d-mmmm h:mm") 20-October 09:41

Date format


Format Syntax Result

Format(Number,"# # # #.# #") 456.68

Format(Number,".# #") 456.68

Format(Number,"0000.00") 0456.68

Format(Number,"000000.00000") 000456.67680

Format(Number,"# # # # #.# # # # #") 456.6768

Format(Number,"# # # # #.0000") 456.6768

Number formatNumber = 456.6768

Format (n, "style argument")Format (n, "style argument")

Format (8972.234, "General Number")Format (8972.2, "Fixed")Format (6648972.265, "Standard")Format (6648972.265, "Currency")Format (0.56324, "Percent")



Control StructuresControl Structures

Branching◦IF

IF Then IF Then – End IF IF Then Else – End IF IF Then Else IF Nested IF

◦Select Case◦Goto

Looping◦While -Wend◦Do while-Loop

◦Do-Loop while◦Do Until-Loop

◦Do-Loop Until◦For next


IF ThenIF Then

Condition Statement1True

False


IF Then – End IFIF Then – End IF

Condition

Statement 1Statement 2Statement 3Statement 4……………..Statement n

True

False


IF Then Else – End IFIF Then Else – End IF

ConditionTrue

False




Statement 1Statement 2Statement 3……………..Statement n

A


B


C

IF <Condition> Then

Else

End IF


IF Then Else IFIF Then Else IF

ConditionTrue

False



Condition

False



True


Statement 1Statement 2……………..Statement n

A


B


C

IF <Condition> Then

Else

End IF


D

ElseIF <Condition> Then


Nested LoopNested Loop

ConditionTrue

False



Condition

False



True

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IF <Condition 2> Then Statement 1Statement 2……………..Statement m

ElseStatement 1Statement 2……………..Statement p

B

C

IF <Condition 1> Then

End IF

Statement 1Statement 2……………..Statement q

D

Else

Select CaseSelect Case

Select case TestExpressionCase Value1

Statement1Case Value2

Statement2Case Value3

Statement3…………………

Case ElseElse Statements

End Select

GoTo StatementGoTo Statement

Label :

Goto LabelorGoto Label

Label :


While -WendWhile -Wend

Condition

Statement 1Statement 2Statement 3

………………Statement n

True

FalseWhile Condition

Statement 1Statement 2……………..Statement

mWend


Do While - LoopDo While - Loop

Condition



True

FalseDo While Condition


mLoop


Do – Loop WhileDo – Loop While

Condition



True

False

DoStatement 1Statement 2……………..Statement

mLoop While Condition


Condition



True

FalseDo Until Condition


mLoop

Do Until - LoopDo Until - Loop


Do – Loop UntilDo – Loop Until

Condition



True

False

DoStatement 1Statement 2……………..Statement

mLoop Until Condition


For counter = start To end [ Step] [ statements 1 ] [ statements 2 ][ statements 2 ]Next [ counter ]

For Next For Next

counter Required in the For statement. Numeric variable. The control variable for the loop. start Required. Numeric expression. The initial value of counter. end Required. Numeric expression. The final value of counter. step Optional. Numeric expression. The amount by which counter is incremented each time through the loop. statements Optional. One or more statements between For and Next that run the specified number of times. Next Required. Terminates the definition of the For loop.


For i = 1 To 7 Print “Visual Basic”Next i

i=1 Visual Basici=2 Visual Basici=3 Visual Basici=4 Visual Basici=5 Visual Basici=6 Visual Basici=7 Visual Basic

For - for loop i - use i as our integer1 - start value = 1 To - between start and stop value7 - stop value = 7Next - go to next step

(if i > 7 then end for loop)


For i = 0 To 9 Print i Next i i=0

i=1i=2i=3i=4i=5i=6i=7i=8i=9


Private Sub Command1_Click()Dim i As IntegerDim j As Integer

For i = 1 To 5 For j = 1 To 7 Print i Next jNext i

End Sub

Inner Loop Outer Loop;

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For i = 1 To 5 For j = 1 To 7 Print j ; Next j

PrintNext iEnd Sub

Inner Loop Outer Loop

i=1j=1j=2j=3j=4j=5j=6j=7

i=2j=1j=2j=3j=4j=5j=6j=7

i=3j=1j=2j=3j=4j=5j=6j=7

i=4j=1j=2j=3j=4j=5j=6j=7

i=5j=1j=2j=3j=4j=5j=6j=7



For i = 1 To 5 For j = 1 To 7 Print i ; Next j

PrintNext iEnd Sub

Inner Loop Outer Loop

i=1j=1 i=1j=2 i=1j=3 i=1j=4 i=1j=5 i=1j=6 i=1j=7 i=1






For i = 1 To 10 For j = 1 To 10 Print j ; Next jPrintNext i

For i = 1 To 10 For j = 1 To 10 Print i ; Next jPrintNext i

For i = 1 To 10 For j = 1 To i Print i ; Next jPrintNext i

For i = 1 To 10 For j = 1 To i Print j ; Next jPrintNext i

For i = 1 To 10 For j = i To 10 Print j ; Next jPrintNext i

For i = 1 To 10 For j = i To 10 Print i ; Next jPrintNext i


Working with Menus in VB6

Visual Basic 6.0

Education

integer dim j

print j nextj print

palitha baddegama

hingurakgoda fori

object references print

subroutines private

integer divisiondiscards

form line