GetDefaultPrinters (WinAPI call) Crashes Labview

[pobrepablo1]

Hi all,

For several reasons I need to use the windows API to get the default printer. I know about labview's activex solutions but those are not universal. 

See attached VI. This winapi call crashes labview rather consistently. It runs fine and returns correctly the default printer. However, some time later, a few seconds or a few operations later it will always crash labview. Why? I've tried changing it to "Run in UI thread" instead of any thread but neither seems to help... 

To get it to crash immediately, try closing the VI. That seems to do it every time. Access violations... 

[pobrepablo1 · Accepted solution]

Solved it. 

This is the definition according to msdn:

BOOL GetDefaultPrinter(
  _In_     LPTSTR pszBuffer,
  _Inout_  LPDWORD pcchBuffer
);

That buffer is pretty important. Although I had allocated more than enough, in the CLN itself I had to select "minimum size" for the pszBuffer to be pcchBuffer. That resolves the crashing. Not sure why this worked...

[zou]

No.  You actually did NOT allocated memory in your VI.

Here is how to allocated memory, the old way:

[zou]

Or you can do it in pure G: