Kung Hei Fat Choi Welcome Back' Todays Lecture: Introduction to Functions , Use of Secondary Storage

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Kung Hei Fat Choi! Welcome Back. Todays
Lecture Introduction to Functions , Use of
Secondary Storage -Files- , a further explanation
of Variables and more VBScript

• Week 5

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As stated in Lecture 3 Files will be covered in
lecture in around two week Review from Lecture
3!

• Files are important to be able to setup record
  keeping systems.
• Today Ill introduce them in lecture since we
  need to assure that you understand the concepts.
• Will be very important for your class project.

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Steps in Reading Data from Files

• 1. Choose a number to be the reference number for
  the file
• 2. Execute an Open statement
• 3. Read the data sequentially using Input
  statements
• 4. Close the file

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Example of Reading from a File

• Open DATA.TXT For Input As 1
• Input 1, num1
• Input 1, num2
• Close 1

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Example of Reading from a File

• Open DATA.TXT For Input As 1 Input 1,
  num1, num2 picOutput.Print num1num2
• Close 1

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Tutorial

• We will go thought the tutorial together,
• The first tutorial is Chapter 14 of the new
  online text. http//www.vbtutor.net/lesson14.html

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The program to Create A text File From the
on-lime tutorial

• Private Sub create_Click() Dim intMsg As String
  Dim StudentName As String
• Open "c\My Documents\sample.txt" For Output As
  1 intMsg MsgBox("File sample.txt opened")
  intMsg MsgBox("File sample.txt opened") Print
  1, StudentName intMsg MsgBox("Writing a"
  StudentName " to sample.txt ")
• Close 1
• intMsg MsgBox("File sample.txt closed")
• End Sub

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Dim Statements

• The first two statements in our tutorial program
  is
• Dim intMsg As String
• Dim StudentName As String
• As we have seen in lecture 3, the Dim statement
  is used to declare variables, for a complete
  explanation of variable go to the following
  hyperlink and read through
• http//www.vbtutor.net/lesson5.html

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This program introduces two new features -
MsgBox and InputBox

• In our progam for today we see the statement
• intMsg MsgBox("File sample.txt opened")
• When this code is executed it will cause a box to
  appear on the screen with the message
• File sample.txt opened
• For an explanation fo MsgBox and InputBox
  functions, go to the following hyperlink
• http//www.vbtutor.net/lesson10.html

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InputBox

• The InputBox gives us a way to input data into a
  file. In our program the code
• intMsg MsgBox("File sample.txt opened")
• This will give us a InputBox on our screen to
  accept data

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Let us now get the program to work

• The first place we have to modify is the path to
  where we want to save the file in Secondary
  storage
• Open "c\My Documents\sample.txt" For Output As
  1

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Upon finishing the program,

• try and get the second program of the tutorial,
  the read program to work on your own
• Private Sub Reading_Click() Dim variable1 As
  String Open "c\My Documents\sample.txt" For
  Input As 1 Input 1, variable1 Text1.Text
  variable1 Close 1
• End Sub
• Go to the hyperlink http//www.vbtutor.net/lesson
  14.html

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VB ability to Access and Manage Data Bases

• If you create a data base with MS Access, Dbase,
  Paradox and etc you can use VB to Access and
  manage the data base
• VB is a tool that makes great user interfaces and
  the tools mentioned above specialize in making
  data Bases.

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Let us examine how we can access an existing
data base

• Go to the document at the hyperlink
• http//www.vbtutor.net/lesson19.html
• Let us go through the tutorial together

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For you final tutorial today, go to our first
on-line textbook

• Go to the lesson on File System Controls
• http//www.kcl.ac.uk/lifelong/vb6/default.htm
• Today we will do only the 1.0 of the tutorial and
  I will guide you through the tutorial.

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VBScript for today!

• Let take up VBScript again by going to an online
  exercise again.
• Let us go to And do the exercise together and
  see the results
• http//www.intranetjournal.com/corner/wrox/progref
  /vbt/ch21_17_first_ex.shtml

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Some things to note!

• In html we have declared a forms as follows
• ltFORM NAME"frmExercise1"gt
• ltINPUT TYPE"Button" NAME"cmdClickMe" VALUE"Clic
  k Me"gt
•   lt/FORMgt
• We use the MsgBox the same way in VBScript as in
  VB 6.0
• MsgBox "A simple example of VBScript in action."
  

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Now you go to the next lesson and do it on your
own.

• Do the lesson, but first let me explain Arrays
• An array is another name for a table. In the
  example of the lesson we have the statements Dim
  States (50) which will set aside 51 locations to
  put in state names.
• It is explained that VB is a Because VBScript
  arrays are zero-based (starts with the first
  element of the array addressed as (0)!

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• In addition, we can have multiple dimensions
  VBScript Arrays.
• For the example, Dim StateInfo(50,1) is a two
  dimension array.
• Exampe of address is StateInfo(18,0)  "Michigan"
  
• StateInfo(18,1)  "Lansing"
• VB supports up to 60 dimensions.
• Go to the Hyperlinkand do the tutorial
• http//www.intranetjournal.com/corner/wrox/progref
  /vbt/ch21_18.shtml

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Conclusions of Todays Lecture

• VB is a powerful user interface tool but does not
  have good secondary storage handling capability.
• VBScript uses many of the same objects but not
  able to define them in an IDE (you normally have
  to code in html.
• Enough information for the first day after a
  holiday week, any questions?