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Type Characters (Visual Basic)

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.

Visual Basic supplies a set of identifier type characters, which 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.

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

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#

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.

The compiler normally construes an integer literal to be in the decimal (base 10) number system. You can force an integer literal to be hexadecimal (base 16) with the &H prefix, and you can force it to be octal (base 8) 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

Octal (base 8)

&O

0-7

&O77

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.

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