Visual Basic 6.0

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Visual Basic 6.0

  1. 1. Palitha Baddegama. Divisional Computer Resource Centre Hingurakgoda Visual basic 6.0
  2. 2. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Form Window Title bar Menu Bar Tool Bar Tool Box Code Window Project Window Property Window Layout Window (IDE) I ntegrated D evelopment E nvironment
  3. 3. Palitha Baddegama , Computer Resource Centre, Hingurakgoda New Project Dialog Box
  4. 4. Palitha Baddegama , Computer Resource Centre, Hingurakgoda
  5. 5. 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.
  6. 6. 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 select one 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 the desired 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 and display 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.
  7. 7. Palitha Baddegama , Computer Resource Centre, Hingurakgoda View Code View Object Toggle Folders Project Name Forms Folder Form & modules
  8. 8. Name Property <ul><li>Must begin with a letter </li></ul><ul><li>Can contain letters, numbers, and the underscore character only </li></ul><ul><li>Must not contain punctuation characters or spaces (!,~,`,@,#,$,%,^,&,*,(,),-,=,+,|,,/,>,<, ,,; ,:) </li></ul><ul><li>Must not exceed 40 characters </li></ul>Palitha Baddegama , Computer Resource Centre, Hingurakgoda
  9. 9. Hungarian Notation <ul><li>Use the three-character IDs shown in Figure 1-10 </li></ul>Palitha Baddegama , Computer Resource Centre, Hingurakgoda 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
  10. 10. <ul><li>Statements </li></ul><ul><li>Procedures </li></ul><ul><ul><li>Event Procedures </li></ul></ul><ul><ul><li>Sub Procedures </li></ul></ul><ul><ul><li>General Procedures </li></ul></ul><ul><ul><li>Functional Procedures </li></ul></ul><ul><li>Comments </li></ul><ul><ul><li>Using single quotation (‘) </li></ul></ul><ul><ul><li>REM </li></ul></ul>Palitha Baddegama , Computer Resource Centre, Hingurakgoda
  11. 11. 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 &quot;Num&quot; to be an Integer Dim vals(5) as Double ' declares an array of 5 Doubles named &quot;vals&quot; Assignment - set values for the variables Num = Num/10 ' after the assignment Num is set to 1/10th of its former value HiString = &quot;Hello &quot; + &quot;World&quot; ' value of HiString is set to &quot;Hello World&quot; Conditionals - do operations depending on the value of one or more variables if Num > 0 then Num = Num * 2 ' Basic logic building block Select 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 steps while ( 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 value Private Function Digit() ' A function returns a value Special statements - used to implement unique features Set MyObject = Your Object 'Set statement assigns object references Print #FileNum, MyObject.Text 'I/O statements like Print, Input Line
  12. 12. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Arithmetic Operators Operator Mathematical function Example ^ Exponential 2^4=16 * Multiplication 4*3=12,   (5*6))2=60 / Division 12/4=3 Mod Modulus(return the remainder from an integer division) 15 Mod 4=3     255 mod 10=5 Integer Division(discards the decimal places) 194=4 + or & String concatenation &quot;Visual&quot;&&quot;Basic&quot;=&quot;Visual Basic&quot;
  13. 13. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Conditional Operators Operator Meaning = Equal to > More than < Less Than >= More than and equal <= Less than and equal <> Not Equal to
  14. 14. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Logical 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
  15. 15. Palitha Baddegama , Computer Resource Centre, Hingurakgoda <ul><li>Variable Names </li></ul><ul><li>The following are the rules when naming the variables in Visual Basic </li></ul><ul><li>It must be less than 255 characters </li></ul><ul><li>No spacing is allowed </li></ul><ul><li>It must not  begin with a number </li></ul><ul><li>Period is not permitted </li></ul><ul><li>Reserved Word not allowed Ex. Sub, Private, </li></ul><ul><li>End </li></ul>Variable and Data Types
  16. 16. Data Types <ul><li>Numeric </li></ul><ul><li>String </li></ul><ul><li>Date </li></ul><ul><li>Boolean </li></ul><ul><li>Object </li></ul><ul><li>Variant </li></ul>Palitha Baddegama , Computer Resource Centre, Hingurakgoda <ul><li>Integer </li></ul><ul><li>Floating point </li></ul><ul><li>Currency </li></ul><ul><li>Byte </li></ul><ul><li>Integer </li></ul><ul><li>Long </li></ul><ul><li>Single </li></ul><ul><li>Double </li></ul>
  17. 17. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Numeric Data Types Type Storage  Range of Values Byte 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).
  18. 18. Palitha Baddegama , Computer Resource Centre, Hingurakgoda   Nonnumeric 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 bytes January 1, 100 to December 31, 9999 Boolean 2 bytes True or False Object 4 bytes Any embedded object Variant(numeric) 16 bytes Any value as large as Double Variant(text) Length+22 bytes Same as variable-length string  
  19. 19. Palitha Baddegama , Computer Resource Centre, Hingurakgoda There are three levels of scope: project-level (also called &quot;global&quot; or &quot;application&quot; 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 Scope
  20. 20. Variable Scope Palitha Baddegama , Computer Resource Centre, Hingurakgoda 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 Module1 Public X as Integer
  21. 21. Palitha Baddegama , Computer Resource Centre, Hingurakgoda MsgBox ( ) Function A=MsgBox(Prompt, Style Value , Title) Example: A =MsgBox( &quot;Click OK to Proceed&quot;, 1 , &quot;Startup Menu&quot;)             A =Msgbox(&quot;Click OK to Proceed&quot;. vbOkCancel ,&quot;Startup Menu&quot;)
  22. 22. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Style Values 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
  23. 23. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Return Values and Command Buttons 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
  24. 24. Palitha Baddegama , Computer Resource Centre, Hingurakgoda testmsg = MsgBox(&quot;Click to test&quot;, 1, &quot;Test message&quot;) testMsg2 = MsgBox(&quot;Click to Test&quot;, vbYesNoCancel + vbExclamation, &quot;Test Message&quot;)
  25. 25. Palitha Baddegama , Computer Resource Centre, Hingurakgoda The Icons displayed in the message box are here Value Named Constant Icon  16 vbCritical 32 vbQuestion 48 vbExclamation 64 vbInformation
  26. 26. Palitha Baddegama , Computer Resource Centre, Hingurakgoda InputBox( ) Function A=InputBox(Prompt, Title, default_text, x-position, y-position) B= InputBox(&quot;What is your message?&quot;, &quot;Message Entry Form&quot;, &quot;Enter your message here&quot;, 500, 700)
  27. 27. <ul><li>The numeric functions </li></ul><ul><li>a) Int Int(2.4)=2, Int(4.8)=4, Int(-4.6)= -5, Int(0.032)=0 and so on. </li></ul><ul><li>b) Sqr Sqr(4)=2, Sqr(9)=3 and etc. </li></ul><ul><li>c) Abs Abs(-8) = 8 and Abs(8)= 8. </li></ul><ul><li>d) Exp Exp(1)=e 1 = 2.7182818284590 </li></ul><ul><li>e) Fix and Int Fix(-6.34)= -6 while Int(-6.34)=-7 </li></ul><ul><li>f) Round Round (7.2567, 2) =7.26 </li></ul><ul><li>g) Log Log 10= 2.302585 </li></ul>Palitha Baddegama , Computer Resource Centre, Hingurakgoda
  28. 28. <ul><li>Len (“welcome to VB tutorial”) = 22 </li></ul><ul><li>Right (&quot;Visual Basic&quot;, 4) = asic </li></ul><ul><li>Left (&quot;Visual Basic&quot;, 4) = Visu </li></ul><ul><li>Ltrim (&quot;  Visual Basic&quot;)= Visual basic </li></ul><ul><li>Rtrim (&quot;Visual Basic      &quot;) = Visual basic </li></ul><ul><li>Trim (&quot;   Visual Basic      &quot;) = Visual basic </li></ul><ul><li>Mid (&quot;Visual Basic&quot;, 3, 6) = sual B </li></ul><ul><li>Instr (1, &quot;Visual Basic&quot;,&quot; Basic&quot;)=8 </li></ul><ul><li>Chr (65)=A, Chr (122)=z, Chr (37)=% , </li></ul><ul><li>Asc (“B&quot;)=66, Asc (“&&quot;)=38 </li></ul>Palitha Baddegama , Computer Resource Centre, Hingurakgoda
  29. 29. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Date format Format Syntax Result Format(Now,&quot; m/d/yy&quot; ) 10/02/09 Format(Now,&quot; dddd,mmmm,dd,yyyy &quot;) Friday,October 02, 2009 Format(Now,&quot; d-mmm &quot;) 02-Oct Format(Now,&quot; mmmm-yyyy &quot;) October -2009 Format(Now,&quot; hh:mm AM/PM&quot;) 09:36 AM Format(Now,&quot; h:mm:ss a/p&quot;) 09:40 a Format(Now,&quot; d-mmmm h:mm &quot;) 20-October 09:41
  30. 30. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Number format Number = 456.6768 Format Syntax Result Format(Number,&quot;# # # #.# #&quot;) 456.68 Format(Number,&quot;.# #&quot;) 456.68 Format(Number,&quot;0000.00&quot;) 0456.68 Format(Number,&quot;000000.00000&quot;) 000456.67680 Format(Number,&quot;# # # # #.# # # # #&quot;) 456.6768 Format(Number,&quot;# # # # #.0000&quot;) 456.6768
  31. 31. Format (n, &quot;style argument&quot;) <ul><li>Format (8972.234, &quot;General Number&quot;) </li></ul><ul><li>Format (8972.2, &quot;Fixed&quot;) </li></ul><ul><li>Format (6648972.265, &quot;Standard&quot;) </li></ul><ul><li>Format (6648972.265, &quot;Currency&quot;) </li></ul><ul><li>Format (0.56324, &quot;Percent&quot;) </li></ul>Palitha Baddegama , Computer Resource Centre, Hingurakgoda
  32. 32. Control Structures <ul><li>Branching </li></ul><ul><ul><li>IF </li></ul></ul><ul><ul><ul><li>IF Then </li></ul></ul></ul><ul><ul><ul><li>IF Then – End IF </li></ul></ul></ul><ul><ul><ul><li>IF Then Else – End IF </li></ul></ul></ul><ul><ul><ul><li>IF Then Else IF </li></ul></ul></ul><ul><ul><ul><li>Nested IF </li></ul></ul></ul><ul><ul><li>Select Case </li></ul></ul><ul><ul><li>Goto </li></ul></ul>Palitha Baddegama , Computer Resource Centre, Hingurakgoda <ul><li>Looping </li></ul><ul><ul><li>While -Wend </li></ul></ul><ul><ul><li>Do while-Loop </li></ul></ul><ul><ul><ul><li>Do-Loop while </li></ul></ul></ul><ul><ul><li>Do Until-Loop </li></ul></ul><ul><ul><ul><li>Do-Loop Until </li></ul></ul></ul><ul><ul><li>For next </li></ul></ul>
  33. 33. IF Then Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition Statement1 True False
  34. 34. IF Then – End IF Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition Statement 1 Statement 2 Statement 3 Statement 4 …………… .. Statement n True False
  35. 35. IF Then Else – End IF Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition True False Statement 1 Statement 2 Statement 3 Statement 4 …………… .. Statement n Statement 1 Statement 2 Statement 3 Statement 4 …………… .. Statement n
  36. 36. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Statement 1 Statement 2 Statement 3 …………… .. Statement n A Statement 1 Statement 2 Statement 3 …………… .. Statement n B Statement 1 Statement 2 Statement 3 …………… .. Statement n C IF <Condition> Then Else End IF
  37. 37. IF Then Else IF Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition True False Statement 1 Statement 2 Statement 3 …………… .. Statement n Statement 1 Statement 2 Statement 3 …………… .. Statement n Condition False Statement 1 Statement 2 Statement 3 …………… .. Statement n Statement 1 Statement 2 Statement 3 …………… .. Statement n True
  38. 38. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Statement 1 Statement 2 …………… .. Statement n A Statement 1 Statement 2 …………… .. Statement n B Statement 1 Statement 2 …………… .. Statement n C IF <Condition> Then Else End IF Statement 1 Statement 2 …………… .. Statement n D ElseIF <Condition> Then
  39. 39. Nested Loop Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition True False Statement 1 Statement 2 Statement 3 …………… .. Statement n Statement 1 Statement 2 Statement 3 …………… .. Statement n Condition False Statement 1 Statement 2 Statement 3 …………… .. Statement n Statement 1 Statement 2 Statement 3 …………… .. Statement n True
  40. 40. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Statement 1 Statement 2 …………… .. Statement n A IF <Condition 2> Then Statement 1 Statement 2 …………… .. Statement m Else Statement 1 Statement 2 …………… .. Statement p B C IF <Condition 1> Then End IF Statement 1 Statement 2 …………… .. Statement q D Else
  41. 41. Select Case <ul><li>Select case TestExpression </li></ul><ul><li>Case Value1 </li></ul><ul><li>Statement1 </li></ul><ul><li>Case Value2 </li></ul><ul><li>Statement2 </li></ul><ul><li>Case Value3 </li></ul><ul><li>Statement3 </li></ul><ul><li>………………… </li></ul><ul><li>Case Else </li></ul><ul><li>Else Statements </li></ul><ul><li>End Select </li></ul>
  42. 42. GoTo Statement <ul><li>Label : </li></ul><ul><li>Goto Label </li></ul><ul><li>or </li></ul><ul><li>Goto Label </li></ul><ul><li>Label : </li></ul>
  43. 43. While -Wend Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition Statement 1 Statement 2 Statement 3 ……………… Statement n True False While Condition Statement 1 Statement 2 …………… .. Statement m Wend
  44. 44. Do While - Loop Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition Statement 1 Statement 2 Statement 3 ……………… Statement n True False Do While Condition Statement 1 Statement 2 …………… .. Statement m Loop
  45. 45. Do – Loop While Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition Statement 1 Statement 2 Statement 3 ……………… Statement n True False Do Statement 1 Statement 2 …………… .. Statement m Loop While Condition
  46. 46. Do Until - Loop Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition Statement 1 Statement 2 Statement 3 ……………… Statement n True False Do Until Condition Statement 1 Statement 2 …………… .. Statement m Loop
  47. 47. Do – Loop Until Palitha Baddegama , Computer Resource Centre, Hingurakgoda Condition Statement 1 Statement 2 Statement 3 ……………… Statement n True False Do Statement 1 Statement 2 …………… .. Statement m Loop Until Condition
  48. 48. For Next Palitha Baddegama , Computer Resource Centre, Hingurakgoda For counter = start To end [  Step ] [ statements 1 ] [ statements 2 ] [ statements 2 ] Next [  counter  ] 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.
  49. 49. Palitha Baddegama , Computer Resource Centre, Hingurakgoda For i = 1 To 7 Print “Visual Basic” Next i i = 1 Visual Basic i = 2 Visual Basic i = 3 Visual Basic i = 4 Visual Basic i = 5 Visual Basic i = 6 Visual Basic i = 7 Visual Basic For - for loop  i - use i as our integer 1 - start value = 1  To - between start and stop value 7 - stop value = 7 Next - go to next step (if i > 7 then end for loop)
  50. 50. Palitha Baddegama , Computer Resource Centre, Hingurakgoda For i = 0 To 9 Print i Next i i= 0 i= 1 i= 2 i= 3 i= 4 i= 5 i= 6 i= 7 i= 8 i= 9
  51. 51. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Private Sub Command1_Click() Dim i As Integer Dim j As Integer For i = 1 To 5 For j = 1 To 7 Print i Next j Next i End Sub Inner Loop Outer Loop ; 1 2 3 4 5 14 21 7 28 35
  52. 52. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Private Sub Command1_Click() Dim i As Integer Dim j As Integer For i = 1 To 5 For j = 1 To 7 Print j ; Next j Print Next i End Sub Inner Loop Outer Loop i=1 j=1 j=2 j=3 j=4 j=5 j=6 j=7 i=2 j=1 j=2 j=3 j=4 j=5 j=6 j=7 i=3 j=1 j=2 j=3 j=4 j=5 j=6 j=7 i=4 j=1 j=2 j=3 j=4 j=5 j=6 j=7 i=5 j=1 j=2 j=3 j=4 j=5 j=6 j=7
  53. 53. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Private Sub Command1_Click() Dim i As Integer Dim j As Integer For i = 1 To 5 For j = 1 To 7 Print i ; Next j Print Next i End Sub Inner Loop Outer Loop i=1 j=1 i =1 j=2 i =1 j=3 i =1 j=4 i =1 j=5 i =1 j=6 i =1 j=7 i =1 i=2 j=1 i =2 j=2 i =2 j=3 i =2 j=4 i =2 j=5 i =2 j=6 i =2 j=7 i =2 i=3 j=1 i =3 j=2 i =3 j=3 i =3 j=4 i =3 j=5 i =3 j=6 i =3 j=7 i =3 i=4 j=1 i =4 j=2 i =4 j=3 i =4 j=4 i =4 j=5 i =4 j=6 i =4 j=7 i =4 i=5 j=1 i =5 j=2 i =5 j=3 i =5 j=4 i =5 j=5 i =5 j=6 i =5 j=7 i =5
  54. 54. Palitha Baddegama , Computer Resource Centre, Hingurakgoda For i = 1 To 10 For j = 1 To 10 Print j ; Next j Print Next i For i = 1 To 10 For j = 1 To 10 Print i ; Next j Print Next i For i = 1 To 10 For j = 1 To i Print i ; Next j Print Next i For i = 1 To 10 For j = 1 To i Print j ; Next j Print Next i For i = 1 To 10 For j = i To 10 Print j ; Next j Print Next i For i = 1 To 10 For j = i To 10 Print i ; Next j Print Next i
  55. 55. Palitha Baddegama , Computer Resource Centre, Hingurakgoda Working with Menus in VB6

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