Global Variables: Counter
A global variable is one that is not declared inside a procedure or function. A global variable can be accessed, changed, or modified anywhere in the program. Variables that are declared inside a procedure or function are local: they can only be used inside the procedure or function where they are declared. We are going to modify the color program by adding a counter. The counter will be declared outside of the procedures, making it global. Write the code as shown below:
Public Class Form1
Dim Number As Integer = 0 'number is global
Private Sub Form1_MouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) _
Handles Me.MouseClick
Dim Red, Green, Blue As Integer ' red, green and blue are local to form1_MouseClick
Number = Number + 1
Red = Rnd() * 255
Green = Rnd() * 255
Blue = Rnd() * 255
Me.BackColor = Color.FromArgb(Red, Green, Blue)
Me.Text = "Color " & Number & " is " & Hex(Red) & Hex(Green) & Hex(Blue) 'shows the hex value of the color
End Sub 'Form1_MouseClick
End Class
INDEX, Introduction to Variables, Assigning Values to a Variable, Short Cut Notations, Global variables
Next lesson: Boolean Expressions in Visual Basic
