Limiting the Amount of Text in a Macro Combo Box or Text Box

The information in this article applies to:

• Microsoft Word for Windows, versions 6.0, 6.0a, 6.0c
• Microsoft Word for Windows 95, version 7.0

SUMMARY

If you create a custom dialog box, you can specify a limit to the amount of text that can be entered into a combo box or text box by using SendMessage (a Windows API function) with the EM_LIMITTEXT constant.

MORE INFORMATION

The preferred way to limit the length of a string entered into a combo or text box is to use the SendMessage API function call. After you set the focus to the desired edit control, you must send a message to the window's message queue that will reset the text limit for the control. The argument EM_LIMITTEXT, as the second parameter to SendMessage, will set the desired text limit based on the value specified by the third argument. The SendMessage function requires the following parameters for setting the text limit

   SendMessage Lib "User"(hWnd As Integer, wMsg As Integer, wParam As
   Integer, lParam As String) As Long

   hWnd     Specifies the handle to the edit control.

   wParam   Specifies the maximum number of bytes that can be entered.
            If the user attempts to enter more characters, the edit
            control beeps and does not accept the characters.

   lParam   Is not used.

Example

WARNING: ANY USE BY YOU OF THE CODE PROVIDED IN THIS ARTICLE IS AT YOUR OWN RISK. Microsoft provides this macro code "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.

Word 7.0

Declare Function GetFocus Lib "User32"() As Long
Declare Function SendMessageA Lib "User32"(hWnd As Long, wMsg As Integer,

Sub MAIN
 WM_USER    = 1024
 EM_LIMITTEXT = WM_USER + 21
 TextLimit = 4     'Sets the number of chars
 Begin Dialog UserDialog 320, 144, "MyApp", .dlgfun
  OKButton 10, 6, 88, 21
  TextBox 10, 30, 160, 18, .TextBox1
  PushButton 10, 51, 88, 21, "Push", .Push1
 End Dialog
 Dim dlg As UserDialog
 Dialog dlg
End Sub

 Select Case action
 Case 1
  DlgVisible "TextBox1", 0
 Case 2
  If id$ = "Push1" Then
   DlgVisible "TextBox1", 1
   DlgFocus "TextBox1"
   hWnd = getfocus
   retVal  = SendMessageA(hWnd, EM_LIMITTEXT, TextLimit, "")
   dlgfun = 1
  End If
 Case 3
 Case 4
 Case 5
 Case 6
 Case Else
 End Select

Word 6.0

Declare Function GetFocus Lib "User"() As Integer
Declare Function SendMessage Lib "User"(hWnd As Integer, wMsg As

Sub MAIN
 WM_USER    = 1024
 EM_LIMITTEXT = WM_USER + 21
 TextLimit = 2     'Sets the number of chars
 Begin Dialog UserDialog 320, 144, "MyApp", .dlgfun
  OKButton 10, 6, 88, 21
  TextBox 10, 30, 160, 18, .TextBox1
  PushButton 10, 51, 88, 21, "Push", .Push1
 End Dialog
 Dim dlg As UserDialog
 Dialog dlg
End Sub

 Select Case action
 Case 1
  DlgVisible "TextBox1", 0
 Case 2
  If id$ = "Push1" Then
   DlgVisible "TextBox1", 1
   DlgFocus "TextBox1"
   hWnd = getfocus
   retVal  = SendMessage(hWnd, EM_LIMITTEXT, TextLimit, "")
   dlgfun = 1
  End If
 Case 3
 Case 4
 Case 5
 Case 6
 Case Else
 End Select

REFERENCES

"Microsoft Software Development Kit (SDK) for Microsoft Windows operating system version 3.1"