VB.NET tutorial: Variables and Data Types


Variables and Data Types

Variable

A variable is what the program used to store value in computer’s memory.

Data type

Data types of variables tell the computer to store different types of values such as number, text string, date, currency, and true/false. They also inform the computer to reserve different memory’s spaces for those variables.

 

Here is the list of data types that can be used in VB.NET.

Data type

Storage size

Range of Value

Byte

1 byte

0 to 255

Boolean

2 bytes

True or False

Integer

2 bytes

-32,768 to 32,767

Long

4 bytes

-2,147,483,648 to 2,147,483,647

Single

4 bytes

-3.402823E38 to -1.401298E-45 for negative values; 1.401298E-45 to 3.402823E38 for positive values

Double

8 bytes

-1.79769313486231E308 to
-4.94065645841247E-324 for negative values; 4.94065645841247E-324 to 1.79769313486232E308 for positive values

Currency

8 bytes

-922,337,203,685,477.5808 to 922,337,203,685,477.5807

Decimal

14 bytes

+/-79,228,162,514,264,337,593,543,950,335 with no decimal point;
+/-7.9228162514264337593543950335 with 28 places to the right of the decimal; smallest non-zero number is
+/-0.0000000000000000000000000001

Date

8 bytes

January 1, 100 to December 31, 9999

Object

4 bytes

Any Object reference

String
(variable-length)

10 bytes + string length

0 to approximately 2 billion

String
(fixed-length)

Length of string

1 to approximately 65,400

Variant
(with numbers)

16 bytes

Any numeric value up to the range of a Double

 

Variant
(with characters)

22 bytes + string length

Same range as for variable-length String

  Data Type Conversion Table

Keyword

Convert to

Allowable data types to be converted

CBool

Boolean

Any numeric type, string, object

CByte

Byte

Any numeric type, Boolean, string, object

CChar

Char

String, object

CDate

Date

String, object

CDbl

Double

Any numeric type, Boolean, string, object

CDec

Decimal

Any numeric type, Boolean, string, object

Cint

Integer

Any numeric type, Boolean, string, object

CLng

Long

Any numeric type, Boolean, string, object

Cobj

Object

Any type

CSng

Single

Any numeric type, Boolean, string, object

CStr

String

Any numeric type, Boolean, char, char(), date, object


Declare and Access Variables

In VB.NET, a variable can be declared using the following prototype:


Dim variable_name As Datatype

To declare a variable, you will use keyword Dim before name of the variable followed by keyword As and type of data to be stored in memory.

Example:
Module Module1
 
    Sub Main()

       'Declaring variables


        Dim x As Integer
        Dim d As Double
        Dim b As Boolean

      'Accessing variables
        x = 10
        d = 122332322
        b = True
        Console.WriteLine("x=" & x)
        Console.WriteLine("d=" & d)
        Console.WriteLine("b=" & b)
        Console.ReadLine()
    End Sub
 
End Module


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