Q181880: PRB: "Access to an Unnamed File Was Denied" Error

Article: Q181880
Product(s): Microsoft C Compiler
Version(s): winnt:4.0,5.0,6.0
Operating System(s): 
Keyword(s): kberrmsg kbCodeGen
Last Modified: 17-JUL-2001

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The information in this article applies to:

- Microsoft Visual C++, version 4.0 
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

You get the following error when calling CFile::Read():

  Access to an unnamed file was denied.

If run under the Microsoft Visual C++ debugger, you will see the following
error:

  CFile exception: accessDenied, File Unknown, OS error information = 5

CAUSE
=====

You are actually opening the file without read access. The following intuitively
correct code causes the error:

  CFile cf;
     int data;
   
     cf.Open("myfile.dat", CFile::modeRead | CFile::modeWrite);
   
     cf.Write(&data, sizeof(int));
   
     cf.Read(&data, sizeof(int));

RESOLUTION
==========

Specify CFile::modeReadWrite instead of the logical OR of CFile::modeRead and
CFile::modeWrite.

STATUS
======

This behavior is by design.

REFERENCES
==========

For more information about CFile, or other MFC classes, consult the Microsoft
Visual C++ online help.
(c) Microsoft Corporation 1998, All Rights Reserved.
Contributions by Joe
Crump, Microsoft Corporation


Additional query words: kbvc400 kbvc500 kbvc600

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Keywords          : kberrmsg kbCodeGen 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbVC500 kbVC600 kbVC32bitSearch kbVC500Search
Version           : winnt:4.0,5.0,6.0
Issue type        : kbprb

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