CFile返回调试断言

Question

I have an old project in Visual C++ and I'm trying to migrate it to Visual Studio 2013. When I verify if a txt file exists, CFile returns debug assertion error. The code is:

if (!txt_file.Open(txt_name,    CFile::modeWrite | CFile::shareDenyWrite  | CFile::typeText))
{
    //action if the file exists
}

What is the problem, I'm doing something wrong ? Thank you

LE :

txt_file is declared as : CStdioFile txt_file in the class trace
txt_name is declared as : private CString txt_name in the method named open_file from class trace
The method open_file contains the if statement that returns debug assertion error.

Answer 1

You are probably using:

CFile txt_file;

CFile does not support text mode.

To open in text mode, you can change to:

CStdioFile txt_file;

That should fix the problem (at least, using CFile in this case generates an assertion).

---

If you are using CStdioFile already, there's probably a problem with the (combination of) open modes. As a test, try to remove CFile::shareDenyWrite . There could be security restrictions too.

mfc\\filecore.cpp Line: 179

It might be best to step through it with the debugger, or have a look at filecore.cpp Line: 179 to see what gets checked there (I would look it up for you, but don't have Visual Studio 2013 at hand right now - probably open modes).

Update :

This is line 179:

// shouldn't open an already open file (it will leak)

ASSERT(m_hFile == INVALID_HANDLE_VALUE);

The file is already opened. So no need to open it again, or first needs to be closed, to open with other open modes.

txt_file.Close();

Or to test if the file is open (not valid for CMemFile ):

if (txt_file.m_hFile != CFile::hFileNull) { // file already open
    txt_file.Close();
}

Answer 2

SOLVED !

Instead of using the piece of code from the question to check if the file exists, I've used the following code :

  CFileStatus sts; //status flag
        bool chkifFileExists = CFile::GetStatus(txt_name, sts); // return TRUE if the file exists else return false




        if (!(chkifFileExists))

{
 //do something
}

Thank you all for your support !