Variables in Visual Basic .NET
Tags: VB.NET, VB 2008, VB 2010, VB 2012, VB 2013
This lesson describes the variables in Visual Basic .NET
Generally speaking, the variables are among the most fundamental components of programming.
A variable is an object that stores a value which can be a number, letter, string, date etc.
If a variable contains a value, the program can manipulate it. Meaning, it can perform arithmetic operations on numbers, string operations on strings (concatenate, calculate substrings, finding a match within string and so on), date operations (find the difference between two dates, add a time period to a date), and so forth.
The variable's behavior is determined by:
1. Scope - it indicates the scope levels from where the variable can be accessed (private, public etc.)
2. Data type - can be an Integer, String, Boolean etc.
3. Accessibility - determines what code in other modules can access the variable
4. Lifetime - determines how long the variable value is valid
For instance, any variable declared inside a subroutine has scope equal to the subroutine and cannot be accessed by the code outside of the subroutine.
Private Sub DoSomething() Dim InsideVariable As String = String.Empty; ' Do Something with the variable End Sub Console.Write(InsideVariable) ' ERROR: variable is not in scope (can't be accessed from outside)
In Visual Basic you use the keyword Dim to tell Visual Basic officially that you want to declare a variable.
You can avoid the Dim only if you specify Private, Public, Protected etc. however a variable delared using a Dim keyword is Private by default so the next two declarations are identical:
Dim MyString As String = String.Empty Private MyString As String = String.EmptyPrevious Lesson | Next Lesson