WD98: How to Break Out of an Infinite Macro Loop

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Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements. In versions of Word earlier than Word 97 for Windows and Word 98 Macintosh Edition, the WordBasic macro language allowed you to break out of macro execution using the ESC key. Beginning with Word 97 for Windows and Word 98 Macintosh Edition, Visual Basic for Applications has replaced WordBasic as the Word for Windows macro language.

There can be many causes for an infinite loop. For, example an infinite loop occurs if you create a loop to check the value of a variable that never changes, as in the following example:

   Sub InfiniteLoop()

      Dim n As Integer
      Dim strMsg As String
      n = 0
      strMsg = "WARNING: This macro will cause an infinite loop. " & vbCr
      strMsg = strMsg & vbCr & "Press OK to continue and then press "
      strMsg = strMsg & "command+.(period) to exit this infinite "
      strMsg = strMsg & "loop or press Cancel to Stop this macro now."
      x = MsgBox(strMsg, vbExclamation + vbOKCancel, "Warning!")
      If x = vbCancel Then n = 1
      Do

         ' Because the "Do...Loop" is looking for the value of 'n'
         ' to equal 1, and because there is no code within the loop
         ' to change the value of the variable 'n' from its initial
         ' value of zero, the "Do...Loop" will continue to loop
         ' indefinitely.

      Loop Until n = 1

   End Sub