supassorn ruenwilai 2/4 43: What is Visual Basic?

What is Visual Basic?

Visual Basic is a tool that allows us to develop Windows (Graphic User Interface - GUI) applications. The applications have a familiar appearance to the user.

Visual Basic is event-driven, meaning code remains idle until it is called upon to respond to some event (e.g. mouse clicking, button pressing, menu selection, ...). Nothing happens until an event is detected. Once an event is detected, the code corresponding to that event (event procedure) is executed.

How to program with Visual Basic?

There are three primary steps involved in building a Visual Basic application:

1. Draw the user interface

2. Assign properties to controls

3. Attach code to controls

Stop Watch Application

1 At the "Start-up Menu" of our Windows Desktop, let's find where "Microsoft Visual Studio 6.0" is, and click on it. Then we can see some shortcuts to the applications of the software suite, and "Microsoft Visual Basic6.0" is one of them and it is also our "target software" right now, let's select it.


At the "Start-up Menu of Windows", Find where the "Microsoft Visual Basic 6.0" is.

2 We now at the main screen of Visual Basic 6.0 with its "New Project" window. Let's click on the "New" tab and select "Standard EXE" icon.

Select the "Standard EXE" icon ให้นักเรียนเลือกสัญรูป Standard EXE

3 Before we go on, let's consider the components of the toolbar of Visual Basic 6.0. Properties window, Run and Save project are what we have to focus on now.

Design View of Visual Basic 6.0 มุม

4 Controls are the genius tools that can be attached by any codes that can control any events such as clicking mouse or pressing key. Now the "Command Button" and the "Label" are the controls that we are going to use.

Controls of Visual Basic 6.0 คอนโทรลต่างๆ ของวิชวลเบสิก 6.0

5 Visual Basic programming begins with a form which has been named "Form1" by default. Visual Basic form simulates itself as platform which can receive many kinds of objects that created by the controls. Any object has its properties that has been shown in the properties window.

Form and Controls are variety kinds of object of Visual Basic that have their own properties.
Form และ Controls เป็นอ็อบเจ็กต์(วัตถุ) ที่หลากหลายของ Visual Basic ที่มี properties ของตนเอง

6 Here we go on creating a design job like the following picture.
    - Using the "Command Button" control to draw the three sequence command buttons, Command1, Command2 and Command3.
   - Using the "Label" control to draw the six sequence labels, Label1,
Label2, Label3, Label4, Label5 and Label6

Form1 would have three command buttons and six labels now.
Form 1 ที่เราออกแบบนี้ก็จะมีปุ่มคำสั่ง (command button) 3 ปุ่ม และมีฉลาก (label) รวม 6 ฉลาก

7 Click on "Form1", we can see its properties, rename it with "frmStopWatch" (frm is a pefix which comes from "form"). And change its caption to "Stop Watch Application".

Form1 Properties Configurations

8 Click on "Command1", yes we are about to specify the properties of this object. Rename it with "cmdStart" (cmd is a prefix which comes from "command button") and also refill its caption with "&Start Timing" (& is a prefix of the key letter that a user can press on this key together with the "alt" key instead of click on this command button).

Change the properties of the command button : name and caption

9 Do it the same way as the previous step.

Change the properties of the command button : name and caption

10 Do it the same way as the previous step.

Change the properties of the command button : name and caption

11 Change only the captions of Label1, Label2 and Label3 according to the following picture.

Change the properties of the three labels : captions เปลี่ยนแค่แค็ปชันของสามเลเบิลแรก

12 Change the properties of the other last three labels, "Label4", "Label5" and "Label6" by renaming them to "lblStart", "lblEnd" and "lblElapsed" and erase their captions until they are blank.

Change the properties of Label4, Label5 and Label6 according to the picture.
เปลี่ยนชื่อของสามเลเบิลท้าย และเคลียร์แค็ปชันให้ว่าง (blank)

13 Now we have just already designed and configured all of related objects, the next step of us is coding our program. Let's click on the menu-bar at the "View" command tab, then select the "Code" sub-command, the view-code window will show up. Yes, we are going to enter our source codes of our application here.

Click on the "View" command at the menu bar, then select "Code" subcommand

14 The first set of source codes is about the declarations. There will be the "(General)" at the left-top of the view-code window and the "(Declarations)" at the right-top. We have to type four lines of our following source codes.

        1st Line is about the General Declaration เป็นคำประกาศทั่วไป
        2nd Line is the Declaration of variable "StartTime" ประกาศตัวแปรเพื่อรับค่าเวลาเริ่มต้น
        3rd Line is the Declaration of variable "EndTime" ประกาศตัวแปรเพื่อรับค่าเวลาที่หยุด
        4th Line is the Declaration of variable "ElapsedTime" ประกาศตัวแปรเพื่อรับค่าเวลาที่ใช้ไป

15 This step is about attaching our source code to a control object. The "cmdStart" is a command button we are going to attach the source code. Let's double click on this command button, yes, this action could bring us to a module or subprogram that could be driven by an event, _click ( ), that means this subprogram could work when this command button was clicked on.

What is about this source code? It begins with assigning the recent time value (Now) to the variable "StartTime". Then the method "Caption" stipulates that the label "lblStart" can show up data from the variable "startTime" with the "hh:mm:ss:" format.

Attach code to the command button "cmdStart"

16 This step is similar to the previous but it turns to the "cmdEnd" command button. But it creates the expression which assigns the variable "ElapsedTime" with the difference of the variable "EndTine" and the variable "StartTine".