Introduction to VB6 Variable Types

Variables provide temporary storage for information that will be needed during the lifespan of the computer program (or application).  This article is short reference table of the types of variables used in programming.

Variables are also used in programming to transfer information from one part of the program to another – for example to provide a place to lay out a document before printing it – as well as being a place to store status information that might be needed by all parts of that program.

While some of the concepts might seem language-specific, they apply to all programming languages to varying degrees, and the terminology is programming language-neutral.

A programmer can imagine a variable as being a box into which information can be placed, and the shape of the box (the variables type) determines what kind of information it can store.

Numeric Data Types

Type	Size	Range of Values	Prefix	Example Variable Name
Byte	1 byte	0 to 255	byt	bytFirstChar
Integer	2 bytes	-32,768 to 32,767	int	intCount
Long	4 bytes	-2,147,483,648 to 2,147,483,648	lng	lngHwnd
Single	4 bytes	Negative values: -3.402823E+38 to -1.401298E-45 Positive values: 1.401298E-45 to 3.402823E+38	sng	sngPi
Double	8 bytes	Negative values: -1.79769313486232e+308 to -4.94065645841247E-324 Positive values: 4.94065645841247E-324 to 1.79769313486232e+308	dbl	dblAngle
Currency	8 bytes	-922,337,203,685,477.5808 to 922,337,203,685,477.5807	cur	curTotalCost

Non-numeric Data Types

Type	Size	Range of Values	Prefix	Example Variable Name
String	Length of string	1 to 65,400 characters (fixed length)	str	strName
String	Length + 10 bytes	0 to 2 billion characters (variable length)	str	strHTML
Date	8 bytes	January 1, 100 to December 31, 9999	dtm	dtmBirth
Boolean	2 bytes	True or False	bln	blnToggle
Object	4 bytes	Any embedded object	obj	objCurrent
Variant	16 bytes	Any value as large as Double (numeric)	vnt	vntNumber
Variant	Length+22 bytes	Same as variable-length string (text)	vnt	vntName