Improved Mid$ Statement

During the course of my work, I often write complex string parsing and manipulation algorithms. The last thing I want, is to have to add more checks to make sure that my string positions are not negative.

I can avoid the hassle by using the following function when I need to use Mid. It wraps around native Visual Basic functionality and handles this common error case.

public Function FlexiMid(From as string, Start as Long, _
       optional Length as Long = -1) as string

    If Start < 1 then Start = 1
    FlexiMid = IIf(Length = -1, mid$(From, Start), _
               mid$(From, Start, Length))

End Function

Once you've pasted this function into your program (I recommend a module, so that you can access it from anywhere), you can use it just as you would Mid. In fact, once I wrote this, I ran a search and replace on my project to start using it.


  • MID$

    Posted by Legacy on 08/19/2002 12:00am

    Originally posted by: Arjen Stins

    public Function FlexiMid(From as string, Start as Long, optional Length as Long = -1) as string
    If Start < 1 then Start = 1
    If Length < 1 Then
    FlexiMid = mid$(From, Start)
    FlexiMid = mid$(From, Start, Length)
    End if
    End Function

    Don't use iif with functions in true and false part.
    They are both evaluated. In the original FlexiMid, all mid$ are processed, but only 1 result is returned.

    In this Flexmid only the mid$ that's returned is processed.

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