Anomaly click in VB6

[habchi]

Hello everybody,

So, it's my first post in this furum, and I hope that I get a solution:

In fact, I have a probleme when I call a dll function and I see an anomaly:
- I puted a fuction under a button
- when I clkik on this button it seems that anithing does happen
- but when I was a little nurvous , I clicked 6 or 7 times on the same button and WOW, it return what I expect !!!
- it's repeatable and it's not acceptable for me and I wanna get the information from the first click

here is the code under button

CompleteSNR = getSerialNumberForAttrib(1, "STR1", "STR2", "STR3")
MsgBox (CompleteSNR)


and here is the declaration of this function :

Declare Function getSerialNumberForAttrib Lib "C:\EnvCIM\itacDllCVI.dll" (ByVal sessionID As Integer, ByVal stationNr As String, ByVal attributeCode As String, ByVal attributeValue As String) As String

and for informaion : the dll was developped under CVI labview

Thank you in advance

[habchi]

is it may be a leak of memory ?
if yes, how can I handel this ?

[DataMiser]

So are you saying that you have to click the button 6 or 7 times before you see the msgbox or are you saying you always see the msgbox but it is empty or what?

Also may help if you showed the code for the sub rather than just the one line.

[habchi]

So are you saying that you have to click the button 6 or 7 times before you see the msgbox or are you saying you always see the msgbox but it is empty or what?

Also may help if you showed the code for the sub rather than just the one line.

yes, I see the msgbox only after 6 or 7 times

its the hole code in the sub

Private Sub Command2_Click()

CompleteSNR = getSerialNumberForAttrib(1, "STR1", "STR2", "STR3")

MsgBox (CompleteSNR)


End Sub

[DataMiser]

Place a break point on that line that calls the getserial and run the program then see if it hits the break point when you click the button.
If it does then hit the F8 key to step to the next line and see what happens.

[habchi]

and the strange in this, the function works well when it returns a string in 17 characters but it produce this anomaly when it will be supposed to return a string in 27 characters ( this is a way you can think about)

[habchi]

Place a break point on that line that calls the getserial and run the program then see if it hits the break point when you click the button.
If it does then hit the F8 key to step to the next line and see what happens.

In fact I can't do the debugging ( the dll not allow me to do that: this function is proceded with another function that prepare the area for this ) . so I always generate a new exe and test the functionnality

[DataMiser]

That doesn't make any sense to me. The code you have shown just calls a function there is no reason there that you should not be able to step through the code in the ide

Another option you may consider is add some code to your program to write some data to a log file. In this case have it write something before it calls the function and after it calls the function and if you have some setup function add some logging the as well then run the program, click the button and go have a look at the log file.

[habchi]

That doesn't make any sense to me. The code you have shown just calls a function there is no reason there that you should not be able to step through the code in the ide

Another option you may consider is add some code to your program to write some data to a log file. In this case have it write something before it calls the function and after it calls the function and if you have some setup function add some logging the as well then run the program, click the button and go have a look at the log file.

I did that log file, and it writes only the line before executing the function and after the executing function ( or not executed ) there is no trace.
I guess it crached until executing ...

[DataMiser]

That would indicate that an error is happening in your function and that your program is not handling the error.

Try adding an error trap to the command_click sub

Private Sub Command2_Click()
On Error GoTo ErrTrap
CompleteSNR = getSerialNumberForAttrib(1, "STR1", "STR2", "STR3")

MsgBox (CompleteSNR)
Exit Sub
ErrTrap:
MsgBox "Error " & Err.Number & vbCrLf & Err.Description

End Sub

[LaVolpe]

@DM. Could this be a problem btwn stdCall and CDecl? I don't know anything about that DLL

[DataMiser]

I really don't know, don;t know anything about the dll either, just throwing a couple of things out there in hopes that it helps.

[ChrisE]

Hello Habchi

this spelling just dosn't look wright itacDllCVI.dll

Declare Function getSerialNumberForAttrib Lib "C:\EnvCIM\itacDllCVI.dll" (ByVal sessionID As Integer, ByVal stationNr As String, ByVal attributeCode As String, ByVal attributeValue As String) As String

regards
Chris

[DEXWERX]

I think Lvaolpe might be on to something.

http://www.ni.com/white-paper/3341/en/#toc2

if you want your DLL to be called from environments such as Microsoft Visual Basic, you must declare the functions to export with the __stdcall calling convention.