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Write Your First Visual Basic Program

Lesson 3
Tutorials - Page 1 - Page 2 - Page 3 - Page 4 - Page 5 - Page 6 - Page 7 - Page 8 - Page 9 - Page 10 - Page 11 - Page 12 - Page 13

Setting the BackColor Property (Continue)

Way 2: Using the Colors Constants
First of all, what is Constant?
Constant is a variable that its value can not be changed.
Constant holds a common used value.
For example, the Constant vbRed holds the value
of the red color - &H000000FF&

Instead of writing in your code:

Command1.BackColor = &H000000FF&

You can write:

Command1.BackColor = vbRed

The 2 statements above are identical, because
vbRed = &H000000FF&


Where are these constants came from?
Visual Basic automatic declare them
when the program starts.

Imagine it like as the following code is
automatic being entered to your program:

Dim vbRed As Long
vbRed = &H000000FF&

Dim vbBlue As Long
vbBlue = &H00FF0000&


And so on...

But with one exception: You can't
change the constants value.

For example, the following code is NOT allowed:

vbBlue = 5


There are more Color constants, a partial list:

vbRed, vbBlue, vbBlack, vbGreen, vbWhite, vbYellow


You can declare your own constants.
The constant declaration syntax:

Const MyVariableName = MyVariableValue


For example, the following code will declare a const
variable with the name Piano and the (const) value "abcdef"


Const Piano = "abcdef"


After this declaration, the   Print Piano  
code line will print abcde on the form.

In addition, the following code line will not be allowed:

Piano = "gggg"

Because it's been declared as a Const,
and Const value can not be changed.


To learn more advanced programming techniques like
conditional statements, go to the Conditional Statements Tutorial.

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