Why CFileDialog::GetNextPathName doesn't work when the file path is long?

Question

Using CFileDialog class, I select multiple files placed in a directory with a long path. It's OK when I select only one or two files; but when I select three files at the same time it returns only a part of the third file path. (Looks like it's limited to 512 characters possibly) How can I resolve this?

Answer 1

MFC uses a default buffer of size _MAX_PATH and that's why you are seeing that behavior. Look at dlgfile.cpp for the implementation of CFileDialog::CFileDialog and you will see m_ofn.lpstrFile and m_ofn.nMaxFile being set.

You can specify a larger buffer if you want to. Before calling DoModal you can either access the CFileDialog::m_pOFN member to get a pointer to the OPENFILENAME that the CFileDialog will use and update it directly or call CFileDialog::GetOFN to get a reference to the structure and update that.

Either way you will find this helpful: http://msdn.microsoft.com/en-US/library/ms646839(v=vs.80).aspx

Answer 2

Assuming that your code looks something like this:

CFileDialog dialog(...);
dialog.DoModal();

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Determine the maximum number of files that you wish to support, for example:

#define MAX_FILE_NAMES 256

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Add this before calling DoModal:

CString data;
dialog.m_pOFN->nMaxFile = (MAX_FILE_NAMES*(MAX_PATH+1))+1;
dialog.m_pOFN->lpstrFile = data.GetBuffer((MAX_FILE_NAMES*(MAX_PATH+1))+1);

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Add this after calling DoModal:

data.ReleaseBuffer();