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Problem with GetSaveFileName().. no dialog appears?

PMH4514
PMH4514 asked
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Last Modified: 2012-06-27
I have this code:

      OPENFILENAME of;
      of.lpstrCustomFilter = "*.csv";
      of.hwndOwner = AfxGetMainWnd()->m_hWnd;
      of.lpstrFile = "count.csv";
      of.lpstrInitialDir      = "e:\\";
      of.lpstrDefExt = ".csv";
      
      BOOL bRes = ::GetSaveFileName(&of);


it compiles and runs, but when I call GetSaveFileName, no dialog ever appears and bRes is false.

GetLastError() returns 87, "the paramater is incorrect"

but it's compiling and running, so what's the problem?

All I want to do is open a dialog where the user can choose a path and .CSV filename

thanks
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jkr
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Top Expert 2012

Commented:
>>so what's the problem?

Try

     OPENFILENAME of;
     ZeroMemory(&of,sizeof(of));
     of.lpstrCustomFilter = "*.csv";
     of.hwndOwner = AfxGetMainWnd()->m_hWnd;
     of.lpstrFile = "count.csv";
     of.lpstrInitialDir     = "e:\\";
     of.lpstrDefExt = ".csv";
     
     BOOL bRes = ::GetSaveFileName(&of);

to set all other struct members to NULL.

Author

Commented:
nope, still no dialog, still error 87
jkr
CERTIFIED EXPERT
Top Expert 2012

Commented:
Ooos, I forgot, you need to set the most important member:

     OPENFILENAME of;
     ZeroMemory(&of,sizeof(of));
     of.lStructSize = sizeof(of);

Author

Commented:
nope, same thing still.

Author

Commented:
it doesn't like the file extension stuff.. This pops the dialog :

      OPENFILENAME of;
      ZeroMemory(&of,sizeof(of));
      of.lStructSize = sizeof(of);
//      of.lpstrCustomFilter = "*.csv";
      of.hwndOwner = AfxGetMainWnd()->m_hWnd;
//      of.lpstrFile = "count.csv";
      of.lpstrInitialDir   = "e:\\";
      of.lpstrDefExt = ".csv";

but if those commented lines are included, I get error 87

Author

Commented:
also, in the instance above where I can the dialog to open, if I do enter a filename and then click OK, bRes is true, but none of the OF fields are populated with the filename I provided.

Author

Commented:
additionally (I still need to limit and default to .CSV) but with those lines commented out, the file I provided isn't specified in the OPENFILENAME struct (As I said above) but the GetLastError() is 2 - "The system cannot find the file specified. "

of course it can't, I'm trying to let the user specify a name of a new file! Am I completely mis understanding something here??
CERTIFIED EXPERT
Top Expert 2012
Commented:
Try

of.lpstrFilter = "csv";

"lpstrCustomFilter" is something different:

lpstrCustomFilter
Pointer to a static buffer that contains a *pair* of null-terminated filter strings for preserving the filter pattern chosen by the user.

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>>>> of.lpstr

All these lpstr members need to be writeable buffers cause they are mostly used for in/out operations. If you assign

   of.lpstrFilter = "*.csv";

you assign a (local) const char* to a char* what normally should give a compile error. I would suggest to use writeable char arrays instead or buffers from CString::GetBuffer();

   char szCustomFilter[256] = { '\0' };   // make all chars zero
   strcpy(szCustomFilter, "*.csv");
   of.lpstrCustomFilter = szCustomFilter;

Note, as jkr mentioned some of these members get a list of entries and need to be (finally) terminated by two zero characters. The above technique guarantees that there are (at least) two final zero characters. Moreover, all buffers were writeable.

Doing the same using CString is

   CString strCustomFilter("*.csv\0\0", sizeof("*.csv\0\0"));  // creates a string with length 8 and enough trailing zeroes
   of.lpstrCustomFilter = strCustomFilter.GetBuffer(256);    // don't be stingy

Regards, Alex

Author

Commented:
>> JKR Wrote:
>>Try
>>of.lpstrFilter = "csv";

that did work.

Alex - both of your suggestions created the same error.

Author

Commented:
so, any thoughts as to why once I do get the dialog opened successfully and enter a filename, that the return value is false, with GetLastError() is 2 - "The system cannot find the file specified. "

??

Author

Commented:
uhhh. duh!

nevermind.. I need to be using CFileDialog to allow the user to select a non-existing file.

points awarded
thanks!
>>>> both of your suggestions created the same error.

The error is/was due to the *contents* of your inputs. My suggestions above were regarding the fact that you shouldn't assign literals to input/output arguments cause that could lead to a crash.

The next point is that you should read the documentation thoroughly  cause some of the inputs require two zero characters for termination what might happen by accident when assigning literals but should be made explicity to make it safe for a release version as well..

Regards, Alex


Author

Commented:
gotcha. I missed a few points.
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