Data Types by George Hernandez

Exploring the data types in Visual Basic.

Data Group	Data Type	Prefix	Values	Size (bytes)
bln	Boolean	bln/b	True or False, Yes or No, etc.	2
byt	Byte	byt	0 to 255	1
int	Integer	int/i	+/-32,768	2
int	Long [integer]	lng/l	+/-2,147,483,648	4
fp	Single [-precision floating point]	sng	+/-3.402823E38 to +/-1.401298E-45	4
fp	Double [-precision floating point]	dbl	+/- 4.94065645841247D324 to +/-1.79769313486232D-308	8
mny	Currency	cur	+/-$922,337,203,685,477.5808	8
dtm	Date [-time]	dtm/d	January 1, 100 to December 31, 9999	8
str	String (fixed length)	str/s	1 to roughly 65,400	Length of String
str	String (variable length)	str/s	0 to roughly 2 billion	10 + Length of String
spec	Variant (with numbers)	vnt/v	any value up to double that of the double data type	16
	Object	obj	an object reference either in or out of the application	4
	Err Object	err		Variable
	Collection Object	col		16 * No. in Collection
	User Defined	udt		Variable

The default value of a Boolean is False in Visual Basic.
As a variant, a variable can change its data type on the fly.
Variants can have special values:
- Empty. A value if the variant is brand new and has never been assigned a value. This is not the same a 0 (zero), zero-length string (""), or space ( ).
- Null. Usually indicates unknown or missing data. All other data types will return an error if assigned a null value.
- Error. Special values returned by passing real numbers to the CVErr function.
Here are the various VB functions that convert to particular datatypes:
- CBool
- CByte
- CCur
- CDdate
- CDbl
- CInt
- CLng
- CSng
- CStr
- CVar
- CVErr

You can define your own data type with the Type statement. This is sort of like a quick and dirty object with properties that are just regular data types.

[Public | Private] Type NameOfUDT UDTProperty1 As DataType UDTProperty1 As DataType ... UDTPropertyN As DataType End Type

Type MyDogUDT
    DogName As String
    CollarColor() As Sring
    Age As Integer
End Type

Dim udt1 As MyDogUDT
udt1.DogName = "Rover"

You can also define your own data type with the Enum statement. This is sort of like a data type whose values can be set by name to a preset Long value.

[Public | Private] Enum NameOfUDT EnumMember1 [= LongExpression ] EnumMember1 [= LongExpression ] ... EnumMemberN [= LongExpression ] End Enum

Enum Stooge
    KMoe = 2   'Otherwise 0 by default.
    KLarry     'This is 3, ie 1 greater than the preceding.     
    KCurly = 1 'This would have been 4. 
End Enum

Dim myStooge As Stooge
myStooge = KCurly
MsgBox "Curly is number " & CStr(myStooge)

Page Modified: (Hand noted: 2007-09-20 19:43:52Z) (Auto noted: 2007-11-17 06:37:24Z)