[RESOLVED] System.DivideByZeroException ERROR (just on some computers)

[Netmaster]

Hi,

I made a downloader program which allows you to download files from the internet.
I made the program using VB 2008 and a pc running windows 7 professional 32-bit. I also tested the program on a pc running windows vista home 32-bit, on another one running windows 7 pro 64bit, and on another one running Windows XP 32 bit. It works fine on all of them.

But today I tried it for the first time on other three different PCs running:
-Windows 7 starter (32-bit)
-Windows 7 Home (64-bit)
-Windows XP (32-bit)

On all three of them it gave me an error right after I click the download button:
"System.DivideByZeroException"

this is the exact error (sorry it is in italian):

************** Testo dell'eccezione **************
System.DivideByZeroException: Tentativo di divisione per zero.
   in WindowsApplication1.Form1.Download_DownloadProgressChanged(Object sender, DownloadProgressChangedEventArgs e) in C:\Documents and Settings\Administrator\Desktop\downloader\Form1.vb:riga 221
   in System.Net.WebClient.OnDownloadProgressChanged(DownloadProgressChangedEventArgs e)
   in System.Net.WebClient.ReportDownloadProgressChanged(Object arg)

If I click on "quit" the program closes, if I click on "continue" it just keeps working nice as it should do! (so i do not see the point of this error actually)
(All the PCs have the latest framework 4.0 installed and anything else needed to make the program run correctly)

Now, I figured out that the error happens here:

Dim kbps As Long = kbDownloaded \ Time
        If kbps < 1024 Then
            Label5.Text = String.Format("Download Speed: {0} KB/s", kbps)
        Else
            Label5.Text = String.Format("Download Speed: {0:0.00} MB/s", kbps / 1024)
        End If

So here is what I did to "fix" it (note that I also had to change from backslash "\" to slash "/"):

        If (kbDownloaded / Time) < 1024 Then
            Label5.Text = String.Format("Download Speed: {0} KB/s", kbDownloaded \ Time)
        Else
            Label5.Text = String.Format("Download Speed: {0:0.00} MB/s", (kbDownloaded / Time) / 1024)
        End If

The thing is that right now it gives me a problem with the download speed! If I stop the download and then restart it (from the beginning) the download speed get crazy and it goes like 1kb/s, 2kb/s, 3kb/s, 4kb/s, 5kb/s, 6kb/s,.. and so on.

How is all this even possible?
The program works fine on four different PCs but then it gives that error on three others! Is there a way to fix this problem? I cannot believe that it just random works on some computers and on some other it does not.

One more thing I would like to add is that the versions of windows where the program works are all in English language while the version of windows where the program does not work are all in Italian. Can this make the difference? If so, how can I fix it? I also tried to rebuild the exe on the one pc running windows xp in italian but it did not help! I also tried to rebuild it using visual studio 2010 but no luck

Please help.

Thank you in advance,

Andrea

[formlesstree4]

Change the slash back and perform a check to see if the time is equal to zero. If it is, don't run those. If it isn't, then you're good to go.

[dbasnett]

This happens because "Time" is some very small number, say .4. When you divide using / there isn't a problem, but when you integer divide (\) time is being converted to an integer, and the conversion causes the number to be zero. So a couple of points:

1 - Turn Option Strict On if it isn't.
2 - Check that the divisor isn't zero before dividing!!!
3 - Use normal division and then round accordingly.

        Dim myTime As Double = 0.4

        Dim bytesDownloaded As Integer = 13

        Dim perSec, rps As Double

        If myTime <> 0 Then
            perSec = bytesDownloaded / myTime

            'different rounding choices
            Dim s As String = perSec.ToString("N0")
            Debug.WriteLine(s & " " & perSec.ToString)

            rps = Math.Round(perSec, 0, System.MidpointRounding.AwayFromZero)
            Debug.WriteLine(rps.ToString)

            rps = Math.Round(perSec, 0, System.MidpointRounding.ToEven)
            Debug.WriteLine(rps.ToString)

        Else
            'time zero ???

        End If

[Netmaster]

wow. thanks for your help!

i just did:

If Time > 0 Then
'all the code in the download progress changed
end if

and it works! =O

How is that possible? on some computers it works without the need of the "if" and on some other it does not...?

[Netmaster]

dbasnett sorry i just read your post.
But how it is possible that on some computers it will work?
do you think that if i leave the code as I did I will face some problem later? or not? Right now it is working fine:

If Time > 0 Then
'all the code in the download progress changed
end if

Thank you,


Andrea

[dbasnett]

It could happen on any computer. The fact that it hasn't happened on them all (yet) doesn't mean it won't.

Do the check for 0, then divide using / and use one of the methods to round the resulting value.

[Shaggy Hiker]

I noticed where you stated that it always happened on the Italian computers, but not on the English. That certainly suggests that there is some localization issue going on. What is Time in both systems? If you looked at the value on each system, it might look different, which could provide some insight as to what is happening.

[Netmaster]

basically noe i fixed it with by doing this:

If Time >= 1 Then
'all the code in the download progress changed
end if

It works fine!

Shaggy Hiker the old code actually worked on an italian pc as well (running windows vista 32-bit).
The thing is that on 4 computers, the old code, works great ! ! ! on the other three computers it never works!
I have tried several times already! I really do not know what to say!
The thing is when the error pop out if I click on "Continue" the program works fine!

Anyway, thanks a lot guys! =D

[Shaggy Hiker]

I'd investigate a bit further, but only if you have the Dev environment on one of the computers that it doesn't work further on. Specifically, I would take a look at what was in Time when that condition failed. It may be that there is an obvious answer in those cases, or it could still be puzzling.

[dbasnett]

Don't check for time > 0 and then do integer division (\)! Look at the code I provided.