ACC: Flexible Input Mask for Entering 5- or 9-Digit ZIP Codes

• Microsoft Access versions 1.0, 1.1, 2.0, 7.0, 97

SUMMARY

This article shows you how to create a flexible input mask for entering either 5- or 9-digit ZIP codes in a field on a form.

This article assumes that you are familiar with Visual Basic for Applications and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Visual Basic for Applications, please refer to your version of the "Building Applications with Microsoft Access" manual.

NOTE: Visual Basic for Applications is called Access Basic in Microsoft Access versions 1.x and 2.0. For more information about Access Basic, please refer to the "Introduction to Programming" manual in Microsoft Access version 1.x or the "Building Applications" manual in Microsoft Access version 2.0.

MORE INFORMATION

The method demonstrated in this article uses three user-defined sample Visual Basic (or Access Basic) functions that perform the following tasks:

• Convert the ZIP code into a text string.



• Strip the text string of any parentheses, spaces, or dashes.



• Determine whether the ZIP code contains any alphabetical characters, and if so, terminate the function and alert the user.

1. Create a new module and enter the following line in the Declarations section if it is not already there:
   

   
         Option Explicit 




2. Enter the following code in the module.
   
   NOTE: In the following sample code, an underscore (_) at the end of a line is used as a line-continuation character. Remove the underscore from the end of the line when re-creating this code in Access Basic.
   

   
         Function Zip (zipcode As Control)
   
           'Exit if a null is passed to the function.
           If IsNull(zipcode) Then
             Exit Function
           End If
           If IsThereAlpha(zipcode) Then
             Msgbox "Your Zip Code Contains Letters"
             Exit Function
           Else
             'Strip unwanted characters, leaving only numbers.
             zipcode = ZStrip(zipcode, "-")
             zipcode = ZStrip(zipcode, " ")
             zipcode = ZStrip(zipcode, ")")
             zipcode = ZStrip(zipcode, "(")
   
             'Reformat the character string.
             Select Case Len(zipcode)
               Case 5
                 Screen.ActiveControl = Format(zipcode, "@@@@@")
               Case 9
                 Screen.ActiveControl = Format(zipcode, "@@@@@-@@@@")
               Case Else
                 MsgBox "This is not a valid ZIP Code."
                 Screen.ActiveControl = zipcode
             End Select
           End If
         End Function
   
         Function ZStrip (InZip, StripZip)
           Do While InStr(InZip, StripZip)
             InZip = Mid(InZip, 1, InStr(InZip, StripZip) - 1) & Mid _
             (InZip, InStr(InZip, StripZip) + 1)
           Loop
           ZStrip = InZip
         End Function
   
         Function IsThereAlpha (zipcode) As Integer
            Dim Pos, a_char$, Clean
            Pos = 1
            Clean = 0
            While (Pos <= Len(zipcode) And (Clean = 0))
               a_char$ = Mid(zipcode, Pos, 1)
               If a_char$ >= "0" And a_char$ <= "9" Then
                  Clean = 0
               Else
                  If a_char$ <> "-" Then Clean = 1
               End If
               Pos = Pos + 1
            Wend
            IsThereAlpha = Clean
         End Function 




3. Type the following in the ValidationRule property of the control that contains the zip code:
   
   Len([Control name]) = 5 or Len([Control name]) = 9



4. Type the following for the validation text for the control:
   

   This is not a valid zip code. Zip codes must be 5 or 9 characters in length. Please re-enter the correct zip code.




5. Set the AfterUpdate property of the control on your form that contains the ZIP codes to the expression
   

   =Zip([<controlname>])

   
   where <controlname> is the name of the control that contains the zip codes.

REFERENCES

For more information about using input masks, search the Help Index for "input masks," and then "Create an input mask to control how data is entered in a field or control."

Keywords          : FmsProp 
Version           : 1.0 1.1 2.0 7.0 97
Platform          : WINDOWS 
Issue type        : kbinfo 

Last Reviewed: April 7, 1999