Content


        VB.NET Data
 Declared Data Types
 See also
 
        Type characters
 Identifier type characters
 Literal type characters
  Default literal types
  Forced literal types
 Hexadecimal, binary, and octal literals
 See also
 
        Source/Reference

VB.NET Data

The data type of a programming element refers to what kind of data it can hold and how it stores that data. Data types apply to all values that can be stored in computer memory or participate in the evaluation of an expression. Every variable, literal, constant, enumeration, property, procedure parameter, procedure argument, and procedure return value has a data type.

Declared Data Types

You define a programming element with a declaration statement, and you specify its data type with the As clause. The following table shows the statements you use to declare various elements.

Programming element	Data type declaration
Variable	In a Dim Statement Dim amount As Double Static yourName As String Public billsPaid As Decimal = 0
Literal	With a literal type character; see "Literal Type Characters" in Type Characters Dim searchChar As Char = "." C
Constant	In a Const Statement Const modulus As Single = 4.17825F
Enumeration	In an Enum Statement Public Enum colors
Property	In a Property Statement Property region() As String
Procedure parameter	In a Sub Statement, Function Statement, or Operator Statement Sub addSale(ByVal amount As Double)
Procedure argument	In the calling code; each argument is a programming element that has already been declared, or an expression containing declared elements subString = Left( inputString , 5 )
Procedure return value	In a Function Statement or Operator Statement Function convert(ByVal b As Byte) As String

For a list of Visual Basic data types, see Data Types.

Type characters

In addition to specifying a data type in a declaration statement, you can force the data type of some programming elements with a type character. The type character must immediately follow the element, with no intervening characters of any kind.

The type character is not part of the name of the element. An element defined with a type character can be referenced without the type character.

Identifier type characters

Visual Basic supplies a set of identifier type characters that you can use in a declaration to specify the data type of a variable or constant. The following table shows the available identifier type characters with examples of usage.

Identifier type character	Data type	Example
%	Integer	Dim L%
&	Long	Dim M&
@	Decimal	Const W@ = 37.5
!	Single	Dim Q!
#	Double	Dim X#
$	String	Dim V$ = "Secret"

No identifier type characters exist for the Boolean, Byte, Char, Date, Object, SByte, Short, UInteger, ULong, or UShort data types, or for any composite data types such as arrays or structures.

In some cases, you can append the $ character to a Visual Basic function, for example Left$ instead of Left, to obtain a returned value of type String.

In all cases, the identifier type character must immediately follow the identifier name.

Literal type characters

A literal is a textual representation of a particular value of a data type.

Default literal types

The form of a literal as it appears in your code ordinarily determines its data type. The following table shows these default types.

Textual form of literal	Default data type	Example
Numeric, no fractional part	Integer	2147483647
Numeric, no fractional part, too large for Integer	Long	2147483648
Numeric, fractional part	Double	1.2
Enclosed in double quotation marks	String	"A"
Enclosed within number signs	Date	#5/17/1993 9:32 AM#

Forced literal types

Visual Basic supplies a set of literal type characters, which you can use to force a literal to assume a data type other than the one its form indicates. You do this by appending the character to the end of the literal. The following table shows the available literal type characters with examples of usage.

Literal type character	Data type	Example
S	Short	I = 347S
I	Integer	J = 347I
L	Long	K = 347L
D	Decimal	X = 347D
F	Single	Y = 347F
R	Double	Z = 347R
US	UShort	L = 347US
UI	UInteger	M = 347UI
UL	ULong	N = 347UL
C	Char	Q = "."C

No literal type characters exist for the Boolean, Byte, Date, Object, SByte, or String data types, or for any composite data types such as arrays or structures.

Literals can also use the identifier type characters (%, &, @, !, #, $), as can variables, constants, and expressions. However, the literal type characters (S, I, L, D, F, R, C) can be used only with literals.

In all cases, the literal type character must immediately follow the literal value.

Hexadecimal, binary, and octal literals

The compiler normally interprets an integer literal to be in the decimal (base 10) number system. You can also define an integer literal as a hexadecimal (base 16) number with the &H prefix, as a binary (base 2) number with the &B prefix, and as an octal (base 8) number with the &O prefix. The digits that follow the prefix must be appropriate for the number system. The following table illustrates this.

Number base	Prefix	Valid digit values	Example
Hexadecimal (base 16)	&H	0-9 and A-F	&HFFFF
Binary (base 2)	&B	0-1	&B01111100
Octal (base 8)	&O	0-7	&O77

Starting in Visual Basic 2017, you can use the underscore character (_) as a group separator to enhance the readability of an integral literal. The following example uses the _ character to group a binary literal into 8-bit groups:

Dim number As Integer = &B00100010_11000101_11001111_11001101

You can follow a prefixed literal with a literal type character. The following example shows this.

Dim counter As Short = &H8000S
Dim flags As UShort = &H8000US

In the previous example, counter has the decimal value of -32768, and flags has the decimal value of +32768.

Starting with Visual Basic 15.5, you can also use the underscore character (_) as a leading separator between the prefix and the hexadecimal, binary, or octal digits. For example:

Dim number As Integer = &H_C305_F860

To use the underscore character as a leading separator, you must add the following element to your Visual Basic project (*.vbproj) file:

XML

<PropertyGroup>
  <LangVersion>15.5</LangVersion>
</PropertyGroup>

For more information see setting the Visual Basic language version.

Source/Reference

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ID: 200900017 Last Updated: 9/17/2020 Revision: 0 Ref:

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