Microsoft Visual Basic 2010 Step by Step eBook

128 Part II Programming Fundamentals

The form contains two labels and two buttons. You’ll use variables to display

information in each of the labels.

Note The label objects look like boxes because I set their BorderStyle properties to Fixed3D.

5. Double-click the Show button.

The Button1_Click event procedure appears in the Code Editor.

6. Type the following program statements to declare and use the LastName variable:

Dim LastName As String

LastName = "Luther"

Label1.Text = LastName

LastName = "Bodenstein von Karlstadt"

Label2.Text = LastName

The program statements are arranged in three groups. The first statement declares

the LastName variable by using the Dim statement and the String type. After you

type this line, Visual Studio places a green jagged line under the LastName variable,

because it has been declared but not used in the program. There is nothing wrong

here—Visual Studio is just reminding you that a new variable has been created and is

waiting to be used.

Tip If the variable name still has a jagged underline when you finish writing your program, it

could be a sign that you misspelled a variable name somewhere within your code.

The second and third lines assign the name “Luther” to the LastName variable and

then display this name in the first label on the form. This example demonstrates

one of the most common uses of variables in a program—transferring information

to a property. As you have seen before, all string values assigned to variables are

displayed in red type.

The fourth line assigns the name “Bodenstein von Karlstadt” to the LastName variable

(in other words, it changes the contents of the variable). Notice that the second string

is longer than the first and contains a few blank spaces. When you assign text strings

to variables, or use them in other places, you need to enclose the text within quotation

marks. (You don’t need to do this with numbers .)

Finally, keep in mind another important characteristic of the variables being declared

in this event procedure—they maintain their scope, or hold their value, only within the

event procedure you’re using them in. Later in this chapter, you’ll learn how to declare

variables so that they can be used in any of your form’s event procedures.