ACC: Flexible Input Mask for Entering Five- or Nine-Digit ZIP Codes (120377)

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.

To set up the input mask, follow these steps:

Create a new module and enter the following line in the Declarations section if it is not already there:
```
      Option Explicit
						
```

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

Type the following in the ValidationRule property of the control that contains the zip code:

Len([Control name]) = 5 or Len([Control name]) = 9
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.
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.

ACC: Flexible Input Mask for Entering Five- or Nine-Digit ZIP Codes (120377)

SUMMARY

MORE INFORMATION

REFERENCES