6. VB.Net - Data Types

 

Data types refer to an extensive system used for declaring variables or functions of different types. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted.

Data Types Available in VB.Net

VB.Net provides a wide range of data types. The following table shows all the data types available:

Data Type	Storage Allocation	Value Range
Boolean	Depends on implementing platform	True or False
Byte	1 byte	0 through 255 (unsigned)
Char	2 bytes	0 through 65535 (unsigned)
Date	8 bytes	0:00:00 (midnight) on January 1, 0001 through 11:59:59 PM on December 31, 9999
Decimal	16 bytes	0 through +/-79,228,162,514,264,337,593,543,950,335 (+/-7.9...E+28) with no decimal point; 0 through +/-7.9228162514264337593543950335 with 28 places to the right of the decimal
Double	8 bytes	-1.79769313486231570E+308 through -4.94065645841246544E-324, for negative values 4.94065645841246544E-324 through 1.79769313486231570E+308, for positive values
Integer	4 bytes	-2,147,483,648 through 2,147,483,647 (signed)
Long	8 bytes	-9,223,372,036,854,775,808 through 9,223,372,036,854,775,807(signed)
Object	4 bytes on 32-bit platform 8 bytes on 64-bit platform	Any type can be stored in a variable of type Object
SByte	1 byte	-128 through 127 (signed)
Short	2 bytes	-32,768 through 32,767 (signed)
Single	4 bytes	-3.4028235E+38 through -1.401298E-45 for negative values; 1.401298E-45 through 3.4028235E+38 for positive values
String	Depends on implementing platform	0 to approximately 2 billion Unicode characters
UInteger	4 bytes	0 through 4,294,967,295 (unsigned)
ULong	8 bytes	0 through 18,446,744,073,709,551,615 (unsigned)
User-Defined	Depends on implementing platform	Each member of the structure has a range determined by its data type and independent of the ranges of the other members
UShort	2 bytes	0 through 65,535 (unsigned)

Example

The following example demonstrates use of some of the types:

Module DataTypes
   Sub Main()
      Dim b As Byte
      Dim n As Integer
      Dim si As Single
      Dim d As Double
      Dim da As Date
      Dim c As Char
      Dim s As String
      Dim bl As Boolean
      b = 1
      n = 1234567
      si = 0.12345678901234566
      d = 0.12345678901234566
      da = Today
      c = "U"c
      s = "Me"
      If ScriptEngine = "VB" Then
         bl = True
      Else
         bl = False
      End If
      If bl Then
         'the oath taking
          Console.Write(c & " and," & s & vbCrLf)
          Console.WriteLine("declaring on the day of: {0}", da)
          Console.WriteLine("We will learn VB.Net seriously")
          Console.WriteLine("Lets see what happens to the floating point variables:")
          Console.WriteLine("The Single: {0}, The Double: {1}", si, d)
      End If
      Console.ReadKey()
   End Sub

End Module

When the above code is compiled and executed, it produces the following result:

U and, Me
declaring on the day of: 12/4/2012 12:00:00 PM
We will learn VB.Net seriously
Lets see what happens to the floating point variables:
The Single:0.1234568, The Double: 0.123456789012346

The Type Conversion Functions in VB.Net

VB.Net provides the following in-line type conversion functions:

S.N	Functions & Description
1	CBool(expression) Converts the expression to Boolean data type.
2	CByte(expression) Converts the expression to Byte data type.
3	CChar(expression) Converts the expression to Char data type.
4	CDate(expression) Converts the expression to Date data type
5	CDbl(expression) Converts the expression to Double data type.
6	CDec(expression) Converts the expression to Decimal data type.
7	CInt(expression) Converts the expression to Integer data type.
8	CLng(expression) Converts the expression to Long data type.
9	CObj(expression) Converts the expression to Object type.
10	CSByte(expression) Converts the expression to SByte data type.
11	CShort(expression) Converts the expression to Short data type.
12	CSng(expression) Converts the expression to Single data type.
13	CStr(expression) Converts the expression to String data type.
14	CUInt(expression) Converts the expression to UInt data type.
15	CULng(expression) Converts the expression to ULng data type.
16	CUShort(expression) Converts the expression to UShort data type.

Example:

The following example demonstrates some of these functions:

Module DataTypes
   Sub Main()
      Dim n As Integer
      Dim da As Date
      Dim bl As Boolean = True
      n = 1234567
      da = Today
      Console.WriteLine(bl)
      Console.WriteLine(CSByte(bl))
      Console.WriteLine(CStr(bl))
      Console.WriteLine(CStr(da))
      Console.WriteLine(CChar(CChar(CStr(n))))
      Console.WriteLine(CChar(CStr(da)))
      Console.ReadKey()
   End Sub
End Module

When the above code is compiled and executed, it produces the following result:

True
-1
True
12/4/2012
1
1

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