learn visual basic -- 3, hello world program

in this chapter, we are going to make a hello world prgram. here, i'll demonstrate a few methods and keywords in coding VB programs. codes that you need to type in are written in green and those already written are in pink, so that you can take note of them, copy and paste them into your code window. must thank me for being helpful ok?

creating a project
first things first, you'll have to create a project. for VB users, just open the IDE. for VBA users, we can go to Microsoft Powerpoint (or any other Microsoft office tool), tools>macros>visual basic editor.

in the editor or IDE, go to file>new project. a window pops up and we will now select empty project in VBA or standard EXE in VB. a form is automatically created for you. you can open the project explorer now and view the branch files contained in the project.

working with controls and form
in the project explorer, open the forms folder. you'll see a form1 in VB or a userform1 in VBA. edit the form by double clicking it. the form is now in form mode, in which you can edit it's properties. in code mode however, you'll edit the code for the form and it's control. i will talk about code mode and code window later.

the form is a grey box with a titlebar and the maximise, minimise and close button. all arranged as it would be seen when running as a program independantly. in VB, the toolbox appears on the left hand side by default, while in VBA, the toolbox pops up when you click on the form(or open it from the view menu).

let's look at the toolbox. move your move over the buttons to see its description. take not of these:

label
textbox
commandbutton

we are going to use these three controls in our hello world program later.

place one of each of these three controls on the form by clicking on the button, then move the mouse over the form, and then drag the area of the control on the form. try it. a single click on the controls in the form will change the contents of the properties window. click on the commandbutton you just created in the form. go to the properties window, scroll and look for the property "Caption" in the left column. change the corresponding left column to "Greet". notice that there are two views for the properties, the alphabet and the catergory. both shows the same properties however.

change the properties of the following:

commandbutton
name - cmd1
caption - Greet

label
name - lbl1
caption - This is my first hello world program!

textbox
name - txt1
text - Enter greet message here

we can rewrite the above three instruction as codes as follow:

cmd1.caption = "Greet"
lbl1.caption = "This is my first hello world program!"
txt1.text = "Enter greet message here"

if you have figured out why, then you are very smart. if not, you are not stupid either, and i will tell you what it is later.

working with codes
we are about the enter codes into the program. to bring up the code window, just double click on the commandbutton, which is named "cmd1".

the code window opens. at the top of the code window, you'll see two drop down boxes (textboxes with down arrow at the right). on the left you'll see "cmd1", which refers to the commandbutton you created. on the right, you'll see action "click". below them, you see the codes:

Private Sub cmd1_Click()

End Sub

right in between the two lines, type in the following so that it looks like:

Private Sub cmd1_Click()
MsgBox "Hello friend", , "Hello World"
End Sub

click on the run button in the toolbar. the program is now being tested. click on the command button. and a message box appear with the prompt "Hello friend" and the title "Hello World". go back to the code view by closing the running form either by means of the stop button on the toolbar or the close button on the form. a close look at the code enables you to decipher the meaning.

MsgBox indeed is a keyword for bring up a message box. "Hello friend" and "Hello world" are parameters, a non-fixed or variable content, for use with the MsgBox method. one being the prompt and the other the title. note that they are in double quots ("...") also. try changing the two for different results.

all procedures are enclosed by two lines -- "Private Sub ..." and "End Sub". therefore, a Sub is a procedure in VB. "cmd1_click()" indicates the condition for the procedure to be executed. in this case, "cmd1" refers to the named commandbutton cmd1 and the event of clicking it will execute the procedure. if the commandbutton is named somthing esle like "iloveyou" then it will become "iloveyou_click()". there are other events for a command button if you look at the right drop down box, which is also the event drop down box, and when the left drop down box, or the object drop down box, is set at "cmd1".

so what is the use of the txt1 and lbl1? we will use it now. go back to code view, and enter the code:

Private Sub cmd1_Click()
greeting = txt1.Text
MsgBox greeting, , "Hello World"
End Sub

run the program. type a greeting message in the textbox, such as: good day sir. then click on cmd1. a MsgBox pops up and show the prompt "good day sir" and the title "Hello World". what happened? let's stop the program and go back to the code.

"greeting" is a variable that we defined. it is not in quots, and can be named anything. replace the two appearances of the word word greeting to greet and run the program, you'll get the same results. try it.

a variable can take any value if not resrticted (you can restrict it to a type of value if you want). here, the variable greeting is assigned, with the assignment operator "=" (equals), with the value txt1.text. you can read the whole line as follow and you'll see it is english:

greeting equals to txt1.text.

so what is txt1.text? scroll all the way up to where we first changed properties of objects and read the part again. txt1 is the name of the textbox. and "text" is the property of txt1. therefore, txt1.text means:

value of text of txt1

the dot is called the period, which separates the property from the object.

so here, greeting takes any value, be it a number or a sentence, and becomes that value. and the next line:

MsgBox greeting, , "Hello World"

greeting appears again. from the fist line of code, greeting now has the value of the text of txt1. with this value, greeting acts as the first parameter of MsgBox, which is the prompt for the message box. therefore, the message box brought up show the message you typed in txt1. note once again that greeting is not enclosed by quots.

what the fuss about quots? why keep talking about it. well..it is one very common mistake programmers make. forgetting about the quots. a line of text, a word or sentence with qouts is called a string. a string is a sentence which will appear as it is. just like "Hello friend" appears as Hello Friend but without quots, it can be a line of code or a variable, which does not appear as it is. greeting does not appear as "greeting", it appears as whatever is the value of txt1.text.

for numbers, a number is a number. it cannot be a variable own it's own without alphabets (ie. greeting1 is a variable but 1 is not). you can force it to act like a string if you enclose it in quots. i explain further in the next chapter.

for now, you can learn how to save a project. just click the save button on the toolbar. you'll be asked to save twice, once as a .vbp or visual basic project and the other one as .frm or form. usaually, for simplicity's sake, save both with a common name, thus helloworld.vbp and helloworld.frm.

the .vpb files contains linkage and code information and the .frm files contains form layout information. when you open the files next time, only open the .vbp files and all the other related files will be loaded.

if using VBA, the program is saved together with the .ppt (or the microsoft office you are using VBA from). so opening the .ppt will mean opening the VBA.

continue next chapter