In this article we will see a small example of using constants in . constants are declared with a keyword const .

Example :

     ConstPI As Double = 3.14
   ConstmyStr As String= “*** ***”

The program below is to find the area and perimeter of circle in which we use const .
In the program below we have declared PI as a constant of type double which value is given as 3.14 and
myStr is a const of type string .

It means PI value cannot be changed either at compile time or run-time .
If we try to assign the value to constant it gives a compile time error .
Any Integral or string variables can be declared as constants.
We can also declare constants as public to use it in all the classes in a program.


Module Module1
    Sub Main()
        ‘declaring const variable PI
        ConstPI As Double = 3.14
        ConstmyStr As String= “*** ***”
        Console.WriteLine(myStr) ‘here myStr is a string constant
        Console.WriteLine(“>>> VB.NET Program to find Area and Perimeter of Circle <<<“ & vbLf)
        Console.Write(“Enter radius value: “)
        Dim r As Integer = Convert.ToInt32(Console.ReadLine())  ‘taking radius as input
        Dimarea As Double= PI * r * r  ‘getting area of circle
        Console.WriteLine(“Area of circle is: “ & area)
        ‘if we try to assign a value to PI or myStr , we get compile-time error
        ‘PI = 123
        ‘myStr = “this is new string”;
        Dimperimeter As Double= 2 * PI * r  ‘getting perimeter of circle
        Console.WriteLine(“Perimeter of circle: “ & perimeter)
    End Sub
End Module

Sample Output :

Constants VB.Net Output