INFO: Microsoft Consulting Services Naming Conventions for Visual Basic

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It is a good idea to establish naming conventions for your Visual Basiccode. This article gives you the naming conventions used by MicrosoftConsulting Services (MCS).

This document is a superset of the Visual Basic coding conventions found inthe Visual Basic "Programmer's Guide."

NOTE: The third-party controls mentioned in this article are manufacturedby vendors independent of Microsoft. Microsoft makes no warranty, impliedor otherwise, regarding these controls' performance or reliability.
Naming conventions help Visual Basic programmers:

  • standardize the structure, coding style and logic of an application.
  • create precise, readable, and unambiguous source code.
  • be consistent with other language conventions (most importantly, the Visual Basic Programmers Guide and standard Windows C Hungarian notation).
  • be efficient from a string size and labor standpoint, thus allowing a greater opportunity for longer and fuller object names.
  • define the minimal requirements necessary to do the above.

Setting Environment Options

Use Option Explicit. Declare all variables to save programming time byreducing the number of bugs caused by typos (for example, aUserNameTmp vs.sUserNameTmp vs. sUserNameTemp). In the Environment Options dialog, setRequire Variable Declaration to Yes. The Option Explicit statement requiresyou to declare all the variables in your Visual Basic program.Save Files as ASCII Text. Save form (.FRM) and module (.BAS) files as ASCIItext to facilitate the use of version control systems and minimize thedamage that can be caused by disk corruption. In addition, you can:

  • use your own editor
  • use automated tools, such as grep
  • create code generation or CASE tools for Visual Basic
  • perform external analysis of your Visual Basic code
To have Visual Basic always save files as ASCII text, from the EnvironmentOptions dialog, set the Default Save As Format option to Text.

Object Naming Conventions for Standard Objects

The following tables define the MCS standard object name prefixes. Theseprefixes are consistent with those documented in the Visual BasicProgrammers Guide.
Prefix    Object Type                           Example-------------------------------------------------------ani       Animation button                      aniMailBoxbed       Pen Bedit                             bedFirstNamecbo       Combo box and drop down list box      cboEnglishchk       Checkbox                              chkReadOnlyclp       Picture clip                          clpToolbarcmd (3d)  Command button (3D)                   cmdOk (cmd3dOk)com       Communications                        comFaxctr       Control (when specific type unknown)  ctrCurrentdat       Data control                          datBibliodir       Directory list box                    dirSourcedlg       Common dialog control                 dlgFileOpendrv       Drive list box                        drvTargetfil       File list box                         filSourcefrm       Form                                  frmEntryfra (3d)  Frame (3d)                            fraStyle (fra3dStyle)gau       Gauge                                 gauStatusgpb       Group push button                     gpbChannelgra       Graph                                 graRevenuegrd       Grid                                  grdPriceshed       Pen Hedit                             hedSignaturehsb       Horizontal scroll bar                 hsbVolumeimg       Image                                 imgIconink       Pen Ink                               inkMapkey       Keyboard key status                   keyCapslbl       Label                                 lblHelpMessagelin       Line                                  linVerticallst       List box                              lstPolicyCodesmdi       MDI child form                        mdiNotempm       MAPI message                          mpmSentMessagemps       MAPI session                          mpsSessionmci       MCI                                   mciVideomnu       Menu                                  mnuFileOpenopt (3d)  Option Button (3d)                    optRed (opt3dRed)ole       OLE control                           oleWorksheetout       Outline control                       outOrgChartpic       Picture                               picVGApnl3d     3d Panel                              pnl3drpt       Report control                        rptQtr1Earningsshp       Shape controls                        shpCirclespn       Spin control                          spnPagestxt       Text Box                              txtLastNametmr       Timer                                 tmrAlarmvsb       Vertical scroll bar                   vsbRate				

Object Naming Convention for Database Objects

Prefix        Object Type          Example------------------------------------------db            ODBC Database        dbAccountsds            ODBC Dynaset object  dsSalesByRegionfdc           Field collection     fdcCustomerfd            Field object         fdAddressix            Index object         ixAgeixc           Index collection     ixcNewAgeqd            QueryDef object      qdSalesByRegionqry (suffix)  Query (see NOTE)     SalesByRegionQryss            Snapshot object      ssForecasttb            Table object         tbCustomertd            TableDef object      tdCustomers				
NOTE: Using a suffix for queries allows each query to be sorted with itsassociated table in Microsoft Access dialogs (Add Table, List TablesSnapshot).

Menu Naming Conventions

Applications frequently use an abundance of menu controls. As a result, youneed a different set of naming conventions for these controls. Menu controlprefixes should be extended beyond the initial mnu label by adding anadditional prefix for each level of nesting, with the final menu caption atthe end of the name string. For example:
Menu Caption Sequence   Menu Handler NameHelp.Contents           mnuHelpContentsFile.Open               mnuFileOpenFormat.Character        mnuFormatCharacterFile.Send.Fax           mnuFileSendFaxFile.Send.Email         mnuFileSendEmail				
When this convention is used, all members of a particular menu group arelisted next to each other in the object drop-down list boxes (in the codewindow and property window). In addition, the menu control names clearlydocument the menu items to which they are attached.

Naming Conventions for Other Controls

For new controls not listed above, try to come up with a unique threecharacter prefix. However, it is more important to be clear than to stickto three characters.

For derivative controls, such as an enhanced list box, extend the prefixesabove so that there is no confusion over which control is really beingused. A lower-case abbreviation for the manufacturer would also typicallybe added to the prefix. For example, a control instance created from theVisual Basic Professional 3D frame could uses a prefix of fra3d to avoidconfusion over which control is really being used. A command button fromMicroHelp could use cmdm to differentiate it from the standard commandbutton (cmd).

Third-party Controls

Each third-party control used in an application should be listed in theapplication's overview comment section, providing the prefix used for thecontrol, the full name of the control, and the name of the software vendor:
Prefix    Control Type        Vendorcmdm      Command Button      MicroHelp				

Variable and Routine Naming

Variable and function names have the following structure:<prefix><body><qualifier><suffix>
Part          Description                                  Example--------------------------------------------------------------------------<prefix>      Describes the use and scope of the variable. iGetRecordNext<body>        Describes the variable.                      iGetNameFirst<qualifier>   Denotes a derivative of the variable.        iGetNameLast<suffix>      The optional Visual Basic type character.    iGetRecordNext%				

The following tables define variable and function name prefixes that arebased on Hungarian C notation for Windows. These prefixes should be usedwith all variables and function names. Use of old Basic suffixes (such as%, &, #, etc.) are discouraged.

Variable and Function Name Prefixes:
Prefix    Converged    Variable Use         Data Type  Suffix--------------------------------------------------------------------------b         bln          Boolean              Integer    %c         cur          Currency - 64 bits   Currency   @d         dbl          Double - 64 bit      Double     #                       signed quantitydt        dat          Date and Time        Variante         err          Errorf         sng          Float/Single - 32    Single     !                       bit signed                       floating pointh                      Handle               Integer    %i                      Index                Integer    %l         lng          Long - 32 bit        Long       &                       signed quantityn         int          Number/Counter       Integer    %s         str          String               String     $u                      Unsigned - 16 bit    Long       &                       unsigned quantity          udt          User-defined typevnt       vnt          Variant              Varianta                      Array				
NOTE: the values in the Converged column represent efforts to pull togetherthe naming standards for Visual Basic, Visual Basic for Applications, andAccess Basic. It is likely that these prefixes will become Microsoftstandards at some point in the near future.

Scope and Usage Prefixes:
Prefix         Descriptiong              Globalm              Local to module or formst             Static variable(no prefix)    Non-static variable, prefix local to procedurev              Variable passed by value (local to a routine)r              Variable passed by reference (local to a routine)				
Hungarian notation is as valuable in Visual Basic as it is in C. Althoughthe Visual Basic type suffixes do indicate a variable's data type, they donot explain what a variable or function is used for, or how it can beaccessed. Here are some examples:
iSend - Represents a count of the number of messages sent
bSend - A Boolean flag defining the success of the last Send operation
hSend - A Handle to the Comm interface
Each of these variable names tell a programmer something very different.This information is lost when the variable name is reduced to Send%. Scopeprefixes such as g and m also help reduce the problem of name contentionespecially in multi-developer projects.

Hungarian notation is also widely used by Windows C programmers andconstantly referenced in Microsoft product documentation and in industryprogramming books. Additionally, the bond between C programmers andprogrammers who use Visual Basic will become much stronger as the VisualC++ development system gains momentum. This transition will result in manyVisual Basic programmers moving to C for the first time and manyprogrammers moving frequently back and forth between both environments.

The Body of Variable and Routine Names

The body of a variable or routine name should use mixed case and should beas long as necessary to describe its purpose. In addition, function namesshould begin with a verb, such as InitNameArray or CloseDialog.

For frequently used or long terms, standard abbreviations are recommendedto help keep name lengths reasonable. In general, variable names greaterthan 32 characters can be difficult to read on VGA displays.

When using abbreviations, make sure they are consistent throughout theentire application. Randomly switching between Cnt and Count within aproject will lead to unnecessary confusion.

Qualifiers on Variable and Routine Names

Related variables and routines are often used to manage and manipulate acommon object. In these cases, use standard qualifiers to label thederivative variables and routines. Although putting the qualifier after thebody of the name might seem a little awkward (as in sGetNameFirst,sGetNameLast instead of sGetFirstName, sGetLastName), this practice willhelp order these names together in the Visual Basic editor routine lists,making the logic and structure of the application easier to understand.The following table defines common qualifiers and their standard meaning:
Qualifier  Description (follows Body)--------------------------------------------------------------------------First      First element of a set.Last       Last element of a set.Next       Next element in a set.Prev       Previous element in a set.Cur        Current element in a set.Min        Minimum value in a set.Max        Maximum value in a set.Save       Used to preserve another variable that must be reset later.Tmp        A "scratch" variable whose scope is highly localized within the           code. The value of a Tmp variable is usually only valid across           a set of contiguous statements within a single procedure.Src        Source. Frequently used in comparison and transfer routines.Dst        Destination. Often used in conjunction with Source.				

User Defined Types

Declare user defined types in all caps with _TYPE appended to the end ofthe symbol name. For example:
Type CUSTOMER_TYPE      sName As String      sState As String * 2      lID as Long   End Type				
When declaring an instance variable of a user defined type, add a prefix tothe variable name to reference the type. For example:
   Dim custNew as CUSTOMER_TYPE				

Naming Constants

The body of constant names should be UPPER_CASE with underscores (_)between words. Although standard Visual Basic constants do not includeHungarian information, prefixes like i, s, g, and m can be very useful inunderstanding the value and scope of a constant. For constant names, followthe same rules as variables. For Example:
<mnUSER_LIST_MAX   ' Max entry limit for User list (integer value,                     ' local to module)   gsNEW_LINE        ' New Line character string (global to entire                     ' application)				

Variant Data Type

If you know that a variable will always store data of a particular type,Visual Basic can handle that data more efficiently if you declare avariable of that type.

However, the variant data type can be extremely useful when working withdatabases, messages, DDE, or OLE. Many databases allow NULL as a validvalue for a field. Your code needs to distinguish between NULL, 0 (zero),and "" (empty string). Many times, these types of operations can use ageneric service routine that does not need to know the type of data itreceives to process or pass on the data. For example:
   Sub ConvertNulls(rvntOrg As Variant, rvntSub As Variant)      ' If rvntOrg = Null, replace the Null with rvntSub      If IsNull(rvntOrg) Then rvntOrg = rvntSub   End Sub				
The are some drawbacks, however, to using variants. Code statements thatuse variants can sometimes be ambiguous to the programmer. For example:
   vnt1 = "10.01" : vnt2 = 11 : vnt3 = "11" : vnt4 = "x4"   vntResult = vnt1 + vnt2  ' Does vntResult = 21.01 or 10.0111?   vntResult = vnt2 + vnt1  ' Does vntResult = 21.01 or 1110.01?   vntResult = vnt1 + vnt3  ' Does vntResult = 21.01 or 10.0111?   vntResult = vnt3 + vnt1  ' Does vntResult = 21.01 or 1110.01?   vntResult = vnt2 + vnt4  ' Does vntResult = 11x4 or ERROR?   vntResult = vnt3 + vnt4  ' Does vntResult = 11x4 or ERROR?				
The above examples would be much less ambiguous and easier to read, debug,and maintain if the Visual Basic type conversion routines were usedinstead. For Example:
   iVar1 = 5 + val(sVar2)   ' use this (explicit conversion)   vntVar1 = 5 + vntVar2    ' not this (implicit conversion)				

Commenting Your Code

All procedures and functions should begin with a brief comment describingthe functional characteristics of the routine (what it does). Thisdescription should not describe the implementation details (how it does it)because these often change over time, resulting in unnecessary commentmaintenance work, or worse yet, erroneous comments. The code itself and anynecessary in-line or local comments will describe the implementation.

Parameters passed to a routine should be described when their functions arenot obvious and when the routine expects the parameters to be in a specificrange. Function return values and global variables that are changed by theroutine (especially through reference parameters) must also be described atthe beginning of each routine.

Routine header comment blocks should look like this (see the next section"Formatting Your Code" for an example):
Section    Comment Description--------------------------------------------------------------------------Purpose    What the routine does (not how).Inputs     Each non-obvious parameter on a separate line with           in-line commentsAssumes    List of each non-obvious external variable, control, open file,           and so on.Returns    Explanation of value returned for functions.Effects    List of each effected external variable, control, file, and           so on and the affect it has (only if this is not obvious)				
Every non-trivial variable declaration should include an in-line commentdescribing the use of the variable being declared.

Variables, controls, and routines should be named clearly enough that in-line commenting is only needed for complex or non-intuitive implementationdetails.

An overview description of the application, enumerating primary dataobjects, routines, algorithms, dialogs, database and file systemdependencies, and so on should be included at the start of the .BAS modulethat contains the project's Visual Basic generic constant declarations.

NOTE: The Project window inherently describes the list of files in aproject, so this overview section only needs to provide information on themost important files and modules, or the files the Project window doesn'tlist, such as initialization (.INI) or database files.

Formatting Your Code

Because many programmers still use VGA displays, screen real estate must beconserved as much as possible, while still allowing code formatting toreflect logic structure and nesting.

Standard, tab-based, block nesting indentations should be two to fourspaces. More than four spaces is unnecessary and can cause statements to behidden or accidentally truncated. Less than two spaces does notsufficiently show logic nesting. In the Microsoft Knowledge Base, we use athree-space indent. Use the Environment Options dialog to set the defaulttab width.

The functional overview comment of a routine should be indented one space.The highest level statements that follow the overview comment should beindented one tab, with each nested block indented an additional tab. Forexample:
**************************************************************************'Purpose:   Locate first occurrence of a specified user in UserList array.'Inputs:    rasUserList():  the list of users to be searched'           rsTargetUser:   the name of the user to search for'Returns:   the index of the first occurrence of the rsTargetUser'           in the rasUserList array. If target user not found, return -1.'**************************************************************************'VB3Line: Enter the following lines as one lineFunction iFindUser (rasUserList() As String, rsTargetUser as String) _   As Integer   Dim i As Integer           ' loop counter   Dim bFound As Integer      ' target found flag   iFindUser = -1   i = 0   While i <= Ubound(rasUserList) and Not bFound      If rasUserList(i) = rsTargetUser Then         bFound = True         iFindUser = i      End If   WendEnd Function				
Variables and non-generic constants should be grouped by function ratherthan by being split off into isolated areas or special files. Visual Basicgeneric constants such as HOURGLASS should be grouped in a single module(VB_STD.BAS) to keep them separate from application-specific declarations.


Always use an ampersand (&) when concatenating strings, and use the plussign (+) when working with numerical values. Using a plus sign (+) withnon-numerical values, may cause problems when operating on two variants.For example:
   vntVar1 = "10.01"   vntVar2 = 11   vntResult = vntVar1 + vntVar2         ' vntResult =  21.01   vntResult = vntVar1 & vntVar2         ' vntResult = 10.0111				


Variables should always be defined with the smallest scope possible.Global variables can create enormously complex state machines and make thelogic of an application extremely difficult to understand. Global variablesalso make the reuse and maintenance of your code much more difficult.Variables in Visual Basic can have the following scope:
Scope             Variable Declared In:            Visibility--------------------------------------------------------------------------Procedure-level   Event procedure, sub, or         Visible in the                  function                         procedure in which                                                   it is declaredForm-level,       Declarations section of a form   Visible in everyModule-level      or code module (.FRM, .BAS)      procedure in the                                                   form or code                                                   moduleGlobal            Declarations section of a code   Always visible                  module (.BAS, using Global                  keyword)				
In a Visual Basic application, only use global variables when there is noother convenient way to share data between forms. You may want to considerstoring information in a control's Tag property, which can be accessedglobally using the syntax.

If you must use global variables, it is good practice to declare all ofthem in a single module and group them by function. Give the module ameaningful name that indicates its purpose, such as GLOBAL.BAS.

With the exception of global variables (which should not be passed),procedures and functions should only operate on objects that are passed tothem. Global variables that are used in routines should be identified inthe general comment area at the beginning of the routine. In addition, passarguments to subs and functions using ByVal, unless you explicitly want tochange the value of the passed argument.

Write modular code whenever possible. For example, if your applicationdisplays a dialog box, put all the controls and code required to performthe dialog's task in a single form. This helps to keep the application'scode organized into useful components and minimizes its runtime overhead.

Third-party Controls

NOTE: The products discussed below are manufactured by vendors independentof Microsoft. Microsoft makes no warranty, implied or otherwise, regardingthese products' performance or reliability.

The following table lists standard third-party vendor name prefixcharacters to be used with control prefixes:
Vendor               Abbv-------------------------MicroHelp (VBTools)  mPioneer Software     pCrescent Software    cSheridan Software    sOther (Misc)         o				
The following table lists standard third-party control prefixes:
Control         Control     Abbr  Vendor     Example            VBX FileType            Name                                            Name--------------------------------------------------------------------------Alarm           Alarm       almm  MicroHelp  almmAlarm          MHTI200.VBXAnimate         Animate     anim  MicroHelp  animAnimate        MHTI200.VBXCallback        Callback    calm  MicroHelp  calmCallback       MHAD200.VBXCombo Box       DB_Combo    cbop  Pioneer    cbopComboBox       QEVBDBF.VBXCombo Box       SSCombo     cbos  Sheridan   cbosComboBox       SS3D2.VBXCheck Box       DB_Check    chkp  Pioneer    chkpCheckBox       QEVBDBF.VBXChart           Chart       chtm  MicroHelp  chtmChart          MHGR200.VBXClock           Clock       clkm  MicroHelp  clkmClock          MHTI200.VBXButton          Command     cmdm  MicroHelp  cmdmCommandButton  MHEN200.VBX                ButtonButton          DB_Command  cmdp  Pioneer    cmdpCommandButton  QEVBDBF.VBXButton (Group)  Command     cmgm  MicroHelp  cmgmBtton          MHGR200.VBX                Button                (multiple)Button          Command     cmim  MicroHelp  cmimCommandButton  MHEN200.VBX                Button                (icon)CardDeck        CardDeck    crdm  MicroHelp  crdmCard           MHGR200.VBXDice            Dice        dicm  MicroHelp  dicmDice           MHGR200.VBXList Box (Dir)  SSDir       dirs  Sheridan   dirsDirList        SS3D2.VBXList Box (Drv)  SSDrive     drvs  Sheridan   drvsDriveList      SS3D2.VBXList Box (File) File List   film  MicroHelp  filmFileList       MHEN200.VBXList Box (File) SSFile      fils  Sheridan   filsFileList       SS3D2.VBXFlip            Flip        flpm  MicroHelp  flpmButton         MHEN200.VBXScroll Bar      Form Scroll fsrm  MicroHelp  fsrmFormScroll     ???Gauge           Gauge       gagm  MicroHelp  gagmGauge          MHGR200.VBXGraph           Graph       gpho  Other      gphoGraph          XYGRAPH.VBXGrid            Q_Grid      grdp  Pioneer    grdpGrid           QEVBDBF.VBXScroll Bar      Horizontal  hsbm  MicroHelp  hsbmScroll         MHEN200.VBX                Scroll BarScroll Bar      DB_HScroll  hsbp  Pioneer    hsbpScroll         QEVBDBF.VBXGraph           Histo       hstm  MicroHelp  hstmHistograph     MHGR200.VBXInvisible       Invisible   invm  MicroHelp  invmInvisible      MHGR200.VBXList Box        Icon Tag    itgm  MicroHelp  itgmListBox        MHAD200.VBXKey State       Key State   kstm  MicroHelp  kstmKeyState       MHTI200.VBXLabel           Label (3d)  lblm  MicroHelp  lblmLabel          MHEN200.VBXLine            Line        linm  MicroHelp  linmLine           MHGR200.VBXList Box        DB_List     lstp  Pioneer    lstpListBox        QEVBDBF.VBXList Box        SSList      lsts  Sheridan   lstsListBox        SS3D2.VBXMDI Child       MDI Control mdcm  MicroHelp  mdcmMDIChild       ???Menu            SSMenu      mnus  Sheridan   mnusMenu           SS3D3.VBXMarque          Marque      mrqm  MicroHelp  mrqmMarque         MHTI200.VBPicture         OddPic      odpm  MicroHelp  odpmPicture        MHGR200.VBXPicture         Picture     picm  MicroHelp  picmPicture        MHGR200.VBXPicture         DB_Picture  picp  Pioneer    picpPicture        QEVBDBF.VBXProperty Vwr    Property    pvrm  MicroHelp  pvrmPropertyViewer MHPR200.VBX                ViewerOption (Group)  DB_RadioGroup radp Pioneer   radqRadioGroup     QEVBDBF.VBXSlider          Slider      sldm  MicroHelp  sldmSlider         MHGR200.VBXButton (Spin)   Spinner     spnm  MicroHelp  spnmSpinner        MHEN200.VBXSpreadsheet     Spreadsheet sprm  MicroHelp  sprmSpreadsheet    MHAD200.VBXPicture         Stretcher   strm  MicroHelp  strmStretcher      MHAD200.VBXScreen Saver    Screen Saver svrm MicroHelp  svrmSaver          MHTI200.VBXSwitcher        Switcher    swtm  MicroHelp  swtmSwitcher       ???List Box        Tag         tagm  MicroHelp  tagmListBox        MHEN200.VBXTimer           Timer       tmrm  MicroHelp  tmrmTimer          MHTI200.VBXToolBar         ToolBar     tolm  MicroHelp  tolmToolBar        MHAD200.VBXList Box        Tree        trem  MicroHelp  tremTree           MHEN200.VBXInput Box       Input (Text) txtm MicroHelp  inpmText           MHEN200.VBXInput Box       DB_Text     txtp  Pioneer    txtpText           QEVBDBF.VBXScroll Bar      Vertical    vsbm  MicroHelp  vsbmScroll         MHEN200.VBX                Scroll BarScroll Bar      DB_VScroll  vsbp  Pioneer    vsbpScroll         QEVBDBF.VBX				

Article ID: 110264 - Last Review: 12/04/2015 09:56:58 - Revision: 1.1

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