SYMPTOMS
When you use the Mid(), Right(), or Left() function, the following error message may appear:
Run-time error '5': "Invalid procedure call or argument"
CAUSE
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
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.
To keep this error from occurring, 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