Visual Basic 6'0

1
Visual Basic 6.0

• Presented by
• Daniel Smith

2
When to Use Visual Basic

• Developing Graphical User Interfaces
• Similar to webpages in appearance, but without
  the sacrifice of computing power
• Textboxes, images, and other objects
• Using High-Level Protocols
• TCP UDP connections
• SQL databases

3
Limitations

• Compiled executables require local copy of Visual
  Basic 5.0 Runtime Module
• Requires expensive software for development
• Not portable between operating systems

4
Lets Get Started

• Start ? Programs ? CS Apps ? Visual Studio ?
  Visual Basic 6.0
• When it finishes loading, click Open to launch
  a new Standard EXE project

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What are you looking at?

• Canvas

• By double-clicking on anything on this form, you
  launch a window for writing related code.

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What are you looking at?

• Properties Sheet
• Use this to modify design-time attributes of
  any object you place on the canvas.
• Most of these properties can also be changed at
  runtime
• More on this in a minute

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What are you looking at?

• Toolbox
• Here are your brush tips for your canvas.
• Just select the type of object you want and drag
  it out on the canvas.
• Can add more types from built-in libraries.

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Most Common Objects
Label (lbl) To write on the canvas.
Textbox (txt) User input field. Also good for
displaying data.
Button (cmd) Need I explain?
Image (img) and Picture (pic) Can display
pictures on your canvas.
Shapes (shp) To make works of artistic
inspiration.
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First Script

• Double-click on the canvas.
• Type the following code
• msgbox Hello World!
• Run your program by pressing the Blue Arrow near
  the top center of the screen.

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Your Reference Source

• For basic syntax functions
• oregonstate.edu/smithd6/vb/vb.hlp
• Use msdn.com for complex usage
• Visual Tools and Languages ? Visual Studio 6.0 ?
  Visual Basic 6.0 ? Reference ? Language Reference

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Second Script

• Create a Textbox on your form by
• Clicking on the textbox button on the toolbox
  (second row, second column)
• Dragging out a rectangle on your canvas
• Notice that you now have options for modifying
  the Textboxs properties in your Properties
  window.

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Second Script (cont)

• Change some properties of your Textbox.
• Backcolor, Forecolor, Font, etc
• The (Name) property is the name by which you
  will access the textbox from your script.
• Add a button in the same manner

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Naming

• To increase readability of your code, name
  objects with a 3-letter prefix to identify what
  type of object it is.
• txt Textbox lbl Label
• cmd Button (Command) pic Picture
• ex txtInput, cmdSubmit
• Use what seems logical to you.

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Second Script (cont)

• Double-click on the button you added
• You will automatically be taken to where to type
  the code for the event of button press
• Type the following
• msgbox Text1
• (if you renamed Text1, use the new name)

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Second Script (cont)

• As long as youre in the code, delete the msgbox
  Hello World! command.
• Delete just the one line, or
• Delete the whole 3-line function
• Click the Blue Arrow to start the program
• Enter some text into your Textbox
• Click the button

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Lets make our owninstant messenger!

• On your canvas make at least the following
• A Textbox to display the conversation
• Set the (Name) property to txtIn
• Set the Multiline property to true
• A Textbox in which to type messages to send
• Set the (Name) property to txtOut
• A Button to send the message
• Set the (Name) property to cmdSend

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A Simple Chat Client

• Load the winsock object by
• Right-click on the toolbox, select Components
• Check the box for Microsoft Winsock Control
• Press Apply
• Notice it is now on your Toolbox.
• Put a winsock object onto your canvas the same
  way you placed Textboxes and Buttons.
• At runtime the image will not be rendered.

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A Simple Chat Client

• Click on the winsock object on your canvas and
  change the following properties on the Properties
  window
• (Name)
• Change it to tcp1 or anything you like.
• Remotehost
• This is the servers IP
• Remoteport
• The server will operate on this port 3600

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A Simple Chat Client

• Double-Click on the winsock object on the canvas
  to bring up the code.
• At the top-right of the code window, see what
  events this object has.
• By selecting an event from this list, the
  appropriate function is brought up.

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A Simple Chat Client

• Select tcp1_DataArrival and enter the following
  code
• Dim strData as String
• tcp1.GetData strData
• txtIn strData Chr(13) Chr(10) txtIn
• Now when the tcp connection recieves data, it
  will pre-pend it into the Textbox.

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A Simple Chat Client

• Select cmdSend and then cmdSend_Click from the
  top of the code window.
• Enter the following code
• tcp1.SendData txtOut
• txtOut.Text
• When the button is pressed, the text in txtOut
  will be sent out on tcp1.

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A Simple Chat Client

• Select Form1 and then Form1_Load from the top of
  the code window.
• Enter the following code
• tcp1.Connect
• When the program loads, the winsock object (tcp1)
  will connect using the properties you previously
  gave it.

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A Simple Chat Client

• Select Form1 and then Form1_Unload from the top
  of the code window.
• Enter the following code
• tcp1.Close
• This helps to clean up socket connections
  gracefully when you kill the program.

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A Simple Chat Client - Overview

• Private Sub Form1_Load()
• tcp1.Connect
• End Sub
• Private Sub cmdSend_Click()
• tcp1.SendData txtOut
• txtOut.Text ""
• End Sub
• Private Sub tcp1_DataArrival(ByVal bytesTotal As
  Long)
• Dim strData as String
• tcp1.GetData strData
• txtIn strData Chr(13) Chr(10) txtIn
• End Sub
• Private Sub Form1_Unload(Cancel As Integer)
• tcp1.Close
• End Sub

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Give it a Try

• When you SendData, the server running on my
  computer echoes it to everyone connected.
• To run peer-to-peer connections, you must also
  program a server. The code for that looks like

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A Server for One Connection

• Private Sub Form_Load()
• tcp1.Listen
• End Sub
• Private Sub tcp_ConnectionRequest(ByVal requestID
  As Long)
• tcp1.Accept requestID
• End Sub
• Private Sub cmdSend_Click()
• tcp1.SendData txtOut.Text
• txtIn.Text txtOut.Text Chr(13) Chr(10)
  txtIn.Text
• txtOut.Text ""
• End Sub
• Private Sub tcp_DataArrival(ByVal bytesTotal As
  Long)
• tcp1.GetData strData
• txtIn.Text strData Chr(13) Chr(10)
  txtIn.Text
• End Sub

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Menubar Items

• To add items to the drop-down menus at the top of
  your program
• Click on the canvas
• Go to Tools ? Menu Editor

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Compile Your Program

• In order to run your program outside of the
  Visual Basic IDE, goto
• File ? Make Project1.exe
• To change the process name of your program, go
  to
• Project ? Project1 Properties
• Change the Project Name

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Appendix

• The Visual Basic files for the client application
  are available at http//oregonstate.edu/smithd6/v
  b/client/
• The Visual Basic files for the server application
  are available at http//oregonstate.edu/smithd6/v
  b/server/
• Download all files to the same directory