Appendix B Variable Naming Convention

Variables are used to hold values. With that goal in mind, it makes sense to choose names for them that describe their purpose or what they contain. The bigger the project you are working on is, the more important it is to be able to keep track of its variables. Here, we offer some things to keep in mind, including standards.

First, you'll want to keep your naming consistent. So, for example if you use Cnt as a variable in one part of the script and Count in another when you are in fact dealing with the same data, you're very likely to introduce runtime errors by confusing the variables.

Second, it is useful to include the scope of a variable by prefixing with g for global, or l for local (to a subprocedure), for example, gstrCompanyName and lstrDepartmentName .

Finally, one of the best ways to organize variable names is to prefix all variable names you use with a shorthand representation of the data type that the variable will hold. The standard prefixes used to accomplish this are called Hungarian notation.

Here is a listing of data types and their associated Hungarian prefixes, complete with examples of use.

Data Type	Hungarian Prefix	Example	VarType()
Boolean	bln (or bool )	BlnValid	11
Byte	Byt	bytColor	17
Currency	Cur	CurTotal	6
Date or Time	Dtm	dtmMember	7
Double	Dbl	DblTotal	5
Error	Err	errInvalidEmailAddress	10
Integer	Int	intCount	2
Long	Lng	lngHeight	3
Object	Obj	ObjWS	9 or 13
Single	Sng	sngWidth	4
String	Str	strName	8
Variant	Var	varNumber	12

Here is a listing of control types and their associated Hungarian prefixes, complete with examples of use.

Control Type	Hungarian Prefix	Example
Animated button	Ani	AniButton
Check box	Chk	ChkNo
Combo list box	Cbo	CboOS
Command button	Cmd	CmdSend
Common dialog	Dlg	DlgOpen
Frame	Fra	FraOptions
Horizontal scroll bar	Hsb	HsbContrast
Image control	Img	ImgHeading
Label	Lbl	LblText
Line	Lin	LinDivide
List box	Lst	LstDueBy
3D panel	Pnl	PnlMain
Pop-up menu	Mnu	MnuContextSelect
Radio/Option button	Opt	OptIncludeFreeGift
Slider	Sld	SldSetVolume
Spin button	Spn	SpnCounter
Tab strip	Tab	TabOptions
Text box	Txt	TxtComment
Vertical scroll bar	Vsb	VsbSetVolume