Value and reference types in VB.NET

This blog defines Value and reference types in VB.NET.

Value Type

A data type is a value type if it holds the data within its own memory allocation. Value types are stored directly on the stack. Value types can not contain the value null. We assign a value to that variable like this: x=11. When a variable of value type goes out of scope, it is destroyed and it's memory is reclaimed.

Value types include the following:

All numeric data types
Boolean, Char, and Date
All structures, even if their members are reference types
Enumerations, since their underlying type is always SByte, Short, Integer, Long, Byte, UShort, UInteger, or ULong

For example

The following code defines an int type variable. int type is a value type.

Module Module1

Sub Main()

Dim m As Integer = 5

Dim n As Integer = m

m = 3

Console.WriteLine("m=" & m)

Console.WriteLine("n=" & n)

End Sub

End Module

OUTPUT

Reference Type

A reference type contains a pointer to another memory location that holds the data.while Reference types are stored on the run-time heap. Value types can contain the value null. Creating a variable of reference type is a two-step process, declare and instantiate. The first step is to declare a variable as that type. The second step, instantiation, creates the object.

Reference types include the following:

String
All arrays, even if their elements are value types
Class types, such as Form
Delegates

For Example

Module Module1

Sub Main()

Dim objX As New System.Text.StringBuilder(" Rohatash Kumasr")

Dim objY As System.Text.StringBuilder

objY = objX

objX.Replace("World", "Test")

Console.WriteLine(objY.ToString())

End Sub

End Module

OUTPUT