VB.NET

Enter a loop when length is zero

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Join Date: Oct 2007

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Reputation: jamesrobb is an unknown quantity at this point

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jamesrobb

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Enter a loop when length is zero

Oct 9th, 2009

Hi,
Can anyone explain why my code enters a loop when the length of a file is zero. I would expect that the loop below would not be entered if strFile.Length is zero.

strFile = strSubCommittees.Split("|")
For i = 0 To strFile.Length - 1

Next i

Thanks.

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Join Date: Mar 2008

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Reputation: sonia sardana has a little shameless behaviour in the past

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sonia sardana sonia sardana is offline

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Oct 9th, 2009

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
if  strFile.Length <> 0
'Code
end if
if  strFile.Length <> 0
'Code
end if

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Join Date: Oct 2007

Posts: 9

Reputation: jamesrobb is an unknown quantity at this point

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jamesrobb

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Oct 9th, 2009

Yes. I thought of that but I wouldn't of thought you had to as it shouldn't enter the loop if the length is zero. Anyway, thanks for your reply, I guess I'll have to add the extra code.
Thanks.

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Join Date: Sep 2009

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TomW

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Oct 10th, 2009

Your array is not actually zero length, it has a length of one!

strFile is an array. The array can either be "nothing" or have at least one element to it; even if it is blank.
strFile = strSubCommittees.Split("|")
This will automatically assign at least one element to your array, even if it is blank and doesnt actually have a value in that element.

Try this in a console app to see the results:

 Help with Code Tags 
 VB Syntax (Toggle Plain Text) 
    Sub Main()
 
        Dim strCommittees As String = ""
        Dim strFile() As String = Nothing
 
        If strFile Is Nothing Then
            Console.WriteLine("strFile() is nothing")
        Else
            Console.WriteLine("strFile.Length : {0}", strFile.Length)
        End If
 
        Console.WriteLine("'Read blank value into array")
        Console.WriteLine("strCommittees.Split(""|""c)")
 
        strFile = strCommittees.Split("|"c)
        Console.WriteLine("strFile.Length : {0}", strFile.Length)
 
        Console.ReadLine()
 
    End Sub
    Sub Main()

        Dim strCommittees As String = ""
        Dim strFile() As String = Nothing

        If strFile Is Nothing Then
            Console.WriteLine("strFile() is nothing")
        Else
            Console.WriteLine("strFile.Length : {0}", strFile.Length)
        End If

        Console.WriteLine("'Read blank value into array")
        Console.WriteLine("strCommittees.Split(""|""c)")

        strFile = strCommittees.Split("|"c)
        Console.WriteLine("strFile.Length : {0}", strFile.Length)

        Console.ReadLine()

    End Sub