VB.NET Const and read-only member

A constant member is defined at compile time and cannot be changed at run time. A read only member is not known at compile time. Read-only member initialized at run time.
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Constant and Read-Only both perform a similar function on data members but there is few difference in both. A constant member is defined at compile time and cannot be changed at run time. A read only member is not known at compile time. Read-only member initialized at run time. Constants use const keyword for declaration. Constants must be be initialized when declared but read-only does not need initialized when declared. Constant cannot be modified once initialized. Read-only member can have different values depend by code in the constructor. const keyword means the value cannot mutate. Read-only keyword means value can be mutated. Constant member assumed to be a static member.

Code

Imports
System.Runtime.CompilerServices

Module Module1
    Sub Main()
        'pass the radius to the constructor
        Dim circle As New MyClass1(5)
        'Convert integer to string
        Dim radius As String = Convert.ToString(circle.Radius)
         Console.WriteLine("Radius = " & radius)
        Console.WriteLine("Circumference = " & String.Format("{0:N3}", circle.Radius * 2 * MyClass1.Cirumference))
        Console.ReadLine()
    End Sub
    Public Class MyClass1
        'Const member declared and initialized
        'Const must be initialized when declared
        Public Const Cirumference As Double = 2.85415
        'read-only member declare
        Public ReadOnly Radius As Integer
        Public Sub New(Value As Integer)
            Radius = Value
        End Sub
   End Class

End
Module

Output 

output.gif

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