Variables in Visual Basic .NET
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.
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:
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.
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| Private Sub DoSomething() Dim InsideVariable As String = String.Empty; ' Do Something with the variableEnd SubConsole.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:
