A variable is a name of the storage area which can be manipulated in a program. A variable is an identifier which can be changed or it is programmer dependent.

Before we use a variable in a VB.Net program the variable must be declared. Every variable in a Visual Basic program should have a data type which tells the compiler which data is going to store in that variable.

We have already discussed the basic data types that VB.Net provides.

Declaring a variable in VB.Net

In Visual Basic .Net the keyword Dim is used to declare a variable and allocate storage.

The syntax of variable declaration in VB.Net is as follows.

[ < attributelist> ] [ accessmodifier ] [[ Shared ] [ Shadows ] | [ Static ]] 

[ ReadOnly ] Dim [ WithEvents ] variablelist

 

attributelist: It specifies the attributes to be applied to a declared programming element. To use multiple attributes the comma is used for separation.

accessmodifier: It indicates the access level of a programming element such as a variable, constant, class or an enumeration.

The access modifier keywords in VB.Net are Public, Private, Protected, Friend, Protected Friend.

Shared: It is an optional part which is used declare a shared variable. A shared variable is not associated with any specific instance of a class or structure. It is available to all instance of the class or structure.

Shadows: It is also an optional part and is used to indicate that the variable re-declares and hides an identically named element, or set of overloaded elements, in a base class.

Static: A static variable can retain its value even when after the termination of the procedure where it is declared. This is an optional part of the variable declaration.

ReadOnly: The keyword ReadOnly is used to declare a variable as read only, not the write permission. It is also an optional part.

WithEvents: It is an optional part that specifies that the variable is used to respond to events raised by the instance assigned to the variable.

VariablesList: It is the list of variables that to be declared.

Example:

Dim name As String
Dim num As Integer
Dim average As Double

Variable Initialization in VB.Net

The process of assigning values to a variable is called the variable initialization.

In VB.Net the equal sign (=) is used for variable initialization.

Syntax:

variable_name = value;

In VB.Net we can assign values to a variable at the time of declaration or in the running time.

Example:

Variable initializing at the time of declaration

Dim a As integer = 10

Variable initializing after the declaration

Dim a As integer
a = 10

Variable initializing at run time

Dim a As integer
a = b + 10

We can also accept user values directly into a variable as shown below.

Dim limit As Integer
limit = Console.ReadLine()