CAUSE
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This problem occurs when the length argument for the statement is negative.
NOTE: In Word 2.0 for Windows, a negative value in the count argument of
the Mid$(), Right$(), or Left$() functions is ignored and does not generate
an error.
The Mid() function returns a portion of a text string starting at a given
character position. The syntax for the command is
Mid(<string>, <start> [, <length>])
where <string> is the text string to search, <start> is the character
position from which to start, and <length> is the number of characters to
return. If no <length> argument is specified, or if there are fewer than
<length> characters in the text, the function returns all the characters
from the <start> position to the end of the string.
The following sample macro illustrates the error message described in the
"Symptoms" section of this article:
Sub ErrorOccurs()
Dim Test As String
Test = Mid("hello", 1, -1)
MsgBox Test
End Sub
The following sample macro returns the error because the length of the
string variable (Test) minus one is a negative number (0 - 1 = -1):
Sub ErrorOccurs()
Dim Test As String
Dim ReturnText As String
Test = ""
' Empty string, could be passed as an empty dialog
' variable, for example.
ReturnText = Mid(Test, Len(Test) - 1)
End Sub
NOTE: Word 2.0 for Windows ignores a -1 value for the <length> argument. So
in Word 2.0, all the characters from the first character position to the
end of the string appear in the message box. In the first example, the
string "hello" appears.
RESOLUTION
To keep this error from ocurring, first test the length of the string, as
in the following example:
Sub ErrorDoesNotOccur()
Dim Test As String
Dim ReturnText As String
' Empty string, could be passed as an empty dialog
' variable, for example.
Test = ""
' Test the length of the string to ensure
' that subtracting 1 from the length leaves
' at least 1 character.
If Len(Test) - 1 > 0 then
ReturnText = Mid(Test, Len(Test) - 1)
End If
End Sub
REFERENCES
For more information about the Mid, Right, or Left functions, click the
Office Assistant while in the Visual Basic Editor, type "Returning Strings
from Functions," click Search, and then click to view "Returning Strings
from Functions."
NOTE: If the Assistant is hidden, click the Office Assistant button on the
Standard toolbar. If the Assistant is not able to answer your query, please
see the following article in the Microsoft Knowledge Base:
176476 OFF: Office Assistant Not Answering Visual Basic Questions
For more information about getting help with Visual Basic for Applications,
please see the following article in the Microsoft Knowledge Base:
163435 VBA: Programming Resources for Visual Basic for Applications