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Resolved Problem calling external functions

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  1. Steven Sheridan
    Steven Sheridan
  2. PowerBuilder
  3. Friday, 1 July 2022 17:11 PM UTC

 

Recently we upgraded to Powerbuilder 2019 R3 version from an older SAP-supported PB.   We have found an issue with the external call function which looks like is now cutting off the first 2 characters we get back from it. 

We make a call to a C++ Dll cal example -> function long fc_findfirst(string filespec,  REF str_finddata fileinfo) LIBRARY "PB2CShared.dll" alias for "fc_findfirst;Ansi"

When we get back the fileinfo it is cutting off the first 2 characters of the file name.  This is creating issues in our PB program. 

Using the same C++ DLL with the older PB works fine.  The structure of the code did not change on PB or the C++ side. The only change for this call was upgrading powerbuilder. 

 

I am not sure how to fix this issue? Does the new PB support a different way to compile the code to make this work or setting? 

 

the application is build with the pcode just like the older version of PB. it is a 32 bit application just like the older version of PB. 

PB2021 Multi-target workspace one target crashes I...
Datawindow -SaveasFormattedText function
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Roland Smith
Roland Smith Accepted Answer Pending Moderation
  1. Friday, 1 July 2022 18:36 PM UTC
  2. PowerBuilder
  3. # 1

If the DLL is doing what I suspect (using Windows API functions to get a list of files), it can be done directly from PowerBuilder.

https://www.topwizprogramming.com/freecode_filesys.html

 

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Steven Sheridan
Steven Sheridan Accepted Answer Pending Moderation
  1. Friday, 1 July 2022 18:33 PM UTC
  2. PowerBuilder
  3. # 2

So i think the  PROGMA_PACK(1) solved it. i found a setting on the IDE that I can set back to 1 and it looks like it fixed the external calls. 

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Chris Pollach @Appeon
  1. Chris Pollach @Appeon
  2. Saturday, 2 July 2022 02:13 AM UTC
Agreed Miguel ... and better yet, all ANSI SDK calls should be converted to proper UNICODE based calls.
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Miguel Leeuwe
  1. Miguel Leeuwe
  2. Saturday, 2 July 2022 02:18 AM UTC
So true Chris!
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Miguel Leeuwe
  1. Miguel Leeuwe
  2. Saturday, 2 July 2022 02:20 AM UTC
The problem here is that the DLL in question is old and there might not be a more recent version to use Unicode. Probably using Roland's filesys object would be the best solution if that offers the needed functionality.

regards.
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John Fauss
John Fauss Accepted Answer Pending Moderation
  1. Friday, 1 July 2022 17:45 PM UTC
  2. PowerBuilder
  3. # 3

I think Miguel may be correct. If this external DLL uses ANSI strings, it is likely pretty old and may not use the same structure memory-packing/layout schema that is prevalent today. Can you post the exported source of the structure?

You can try including PROGMA_PACK(1) [not "pragma"] after the Alias For clause in the external function declaration and see if that helps. This tells PB to use 1-byte packing alignment for structure members instead of the default so-called 8-byte alignment.

What does the function in the external DLL do? There may be a WinAPI function that accomplishes the same or similar functionality?

Regards, John

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Miguel Leeuwe
Miguel Leeuwe Accepted Answer Pending Moderation
  1. Friday, 1 July 2022 17:28 PM UTC
  2. PowerBuilder
  3. # 4

Hi,

I think you might have to use some ".....pragma pack setting ..." somewhere having to do with how many bits are being used for external functions.

I'm sorry, but I cannot access powerbuilder right now. I'll get back on this later on ...

regards.

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