Looping Statement repetition.

----- Visual Basic 0.6 ( Looping Repetition )
------- GRADE CALCULATOR CODES.



Dim intCount As Integer, strChecked As String

    If chkDone(Index).Value = vbChecked Then
        cmdDisplay.Enabled = True
        txtScore(Index).Enabled = True
        txtScore(Index).SetFocus
    Else
        txtScore(Index).Text = 0
        txtScore(Index).Enabled = False
        strChecked = "N"
        Do While intCount <= 4 And strChecked = "N"
            If chkDone(intCount).Value = vbChecked Then
                strChecked = "y"
            End If
            intCount = intCount + 1
        Loop
        If strChecked = "n" Then
            cmdDisplay.Enabled = False
        End If
    End If
           
   
End Sub

Private Sub cmdClear_Click()
Dim x As Integer

For x = 0 To 4
   chkDone(x).Value = False
   txtScore(x).Text = ""
Next x

lblGrade.Caption = ""
txtName.SetFocus

 
End Sub

Private Sub cmdDisplay_Click()
    Dim intEarned As Integer, intPossible As Integer
    Dim sngRatio As Single, intCount As Integer
   
        For intCount = 0 To 4
            If chkDone(intCount).Value = vbChecked Then
                intEarned = intEarned + Val(txtScore(intCount).Text)
                Select Case intCount
                    Case 0 To 2
                        intPossible = intPossible + 10
                    Case Else
                        intPossible = intPossible + 50
                    End Select
            End If
        Next intCount
       
        sngRatio = intEarned / intPossible
            Select Case sngRatio
                Case Is >= 0.9
                    lblGrade.Caption = "A"
                Case Is >= 0.8
                    lblGrade.Caption = "B"
                Case Is >= 0.7
                    lblGrade.Caption = "C"
                Case Is >= 0.6
                    lblGrade.Caption = "D"
                Case Else
                    lblGrade.Caption = "F"
            End Select
   
End Sub

Private Sub cmdExit_Click()
    Unload frmGrade

End Sub

Private Sub cmdPrint_Click()
    PrintForm
End Sub

Private Sub Form_Load()
    frmGrade.Top = (Screen.Height - frmGrade.Height) / 2
    frmGrade.Left = (Screen.Width - frmGrade.Width) / 2
End Sub

Private Sub Form_Unload(Cancel As Integer)
Const conBtns As Integer = vbYesNo + vbExclamation + vbDefaultButton1 + vbApplicationModal
Dim intUserResponse As Integer

intUserResponse = MsgBox("Do you want to exit?", conBtns, "Grade Application")
If intUserResponse = vbNo Then          'User does not want to quit the app
    Cancel = 1                          'prevent form unload.
End If

End Sub

Private Sub txtScore_GotFocus(Index As Integer)
    txtScore(Index).SelStart = 0
    txtScore(Index).SelLength = Len(txtScore(Index).Text)
   
End Sub

STRUCTURED PROGRAMMING

SELECTION CONSTRUCTS

The Selection constructs are used when the flow of execution may flow down two or more paths.

I compile it in .Exe

 

                            If statements can be nested, and the combined with logical operators.



THE IF STATEMENT

The If statement is used to control the flow of execution down one of two or more paths, depending on the result of a logical test. The Else If statement may be used to specify conditions should previous conditions be false, and Else may be used should none of the above be true. 

of course on the Selection Statement you can see may example below the last topic on our subject.   

-I use the Select Case construct to Access the code, according to which arrow key is pressed on the keyboard or in the screen using the point Cursor. 

The Select statement can be used when multiple If statements become messy and difficult to read. Each Case statement is evaluated from the top down. Should the Case statement be true, the section of code associated with the condition is executed. Case Else is used as a catch all.

Programming Practices

PROGRAM READABILITY

a.) Meaningful Identifiers

      Dim mAccessCode As Long       

           Dim message As String

Declaires the variable mAccessCode as type Long. Like Integer , Long stores whole numbers (w/o decimal point). the rage of the values that can be stored in a Long are-- 2,147,483,648 to 2,147,483,647.

The Long is a type of character &. with m allows them to be identified easily.

b.) Logic Practice 

    Select Case mAccessCode
         Case Is < 1000
             message = "Access Denied"
             Beep
         Case 1645 To 1689
             message = "Technician Personnel"
         Case 8345
             message = "Custodial Services"
         Case 55875
             message = "Special Services"
         Case 999898, 1000006 To 1000008
             message = "Specific Personnel"
         Case Else
             message = "Access Denied"
  End Select

Placing a larger value on the left side of keyword To in a Case is a logic error and is ignored at run-time.

When using the optional Case Else statement in a Select Case structure, not placing the Case Else as the last statement is a syntax error.

c.) Coding Practice

      Case Is < 1000

Keywords Is along with the comparison operator < , specifies the rage of values to test.

d.) Notes and Comments

    Dim message As String

   mAccessCode = txtDisplay.Text

   txtDisplay.Text = ""

PROGRAM DOCUMENTATION

a.) Program Listing

    Private Sub cmdZero_Click()

        txtDisplay.Text = txtDisplay.Text & "0"

  End Sub

I listed the properties for cmdZero, Although i did not use other numbered buttons, they have the same property settings.

b.) Program Specification

Security Keypad
-A Simple Vb Programming, Easy Operation

- It can also a Security Access Control Keypad ( Company User )-For switching locks,entry and security systems.

-Has a limited Users codes.

Numbers combinations are possible for the 4 independent user codes: 

1645 to 1689 (Technician Personnel)

8345 (Custodial Services) 

55875 (Special Services)

999898, 1000006 to 1000008 (Scientific Personnel).

User code 1000 can be altered to act as a Panic code for reporting panic to an "Access Denied".

c.) File Layouts and Record Description

I listed the properties for cmdZero, Although i did not use other numbered buttons, they have the same property settings.

Tthe variable mAccessCode as type Long. Like Integer , Long stores whole numbers (w/o decimal point). 
The rage of the values that can be stored in a Long are-- 2,147,483,648 to 2,147,483,647.

The Long is a type of character &.

 1stLogEntry.AddItem Now & Space$ (3) & message

-It has the ability to record the time and date to the text box and it tells as if it is "Access Denied" or granted.

 Now is the current system time and date.
function Space$(3) creates and returns a string containing spaces.

d.) Operating Instruction

including the Case Else statement focuses the programer on the need to process exceptional conditions.  In some situation s, no Case Else processing is needed.
The required End Select terminates the Select Case structure, such indentation improves program readability.

Look at the file layouts and the Instructions. ( Security Keypad Program GUI ) 

Initial GUI at execution.

User entering an access code.

GUI after user has pressed Enter.


-Code Listing-

 Visual Basic 0.6