Question

I’ve troubles with FindWindow using pywin32 extension.
Simple C code:

int main()
{
  HWND h = FindWindow(NULL, TEXT("SomeApp"));
  if (h != INVALID_HANDLE_VALUE)
      SetForegroundWindow(h);
  return 0;
}

Works well. Same with python:

import win32gui

h = win32gui.FindWindow(None, "SomeApp")
if h:
    win32gui.SetForegroundWindow(h)
else:
    print "SomeApp not found"

Fails, SomeApp not found. I suggest text encoding may be cause trouble here but not found any information in docs how to specify text.

Update:
I’ve tested code on other machine and don’t see any troubles. So, configuration on my first machine should be incorrect. I’ve update my investigation results if found the problem.

Answer 1

In the C code, you are checking h != INVALID_HANDLE_VALUE, in Python h != None. INVALID_HANDLE_VALUE is not 0/null/None.

Python defines win32file.INVALID_HANDLE_VALUE via the win32file import.

Also, instead of printing “SomeApp not found”, you can do something like:

gle = win32api.GetLastError()
err = win32api.FormatMessage(gle)[:-2]
print 'SomeApp not found: LastError=%d - %s' % (gle, err)

This should give you more details on the failure if FindWindow has legitimately failed for some reason (or “Success” if it worked).