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Article ID: 181880 - Last Review: December 8, 2003 - Revision: 2.0

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

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This article was previously published under Q181880
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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
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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));
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RESOLUTION

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

This behavior is by design.
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REFERENCES

For more information about CFile, or other MFC classes, consult the Microsoft Visual C++ online help.
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APPLIES TO
  • Microsoft Visual C++ 4.0 Standard Edition
  • Microsoft Visual C++ 5.0 Enterprise Edition
  • Microsoft Visual C++ 6.0 Enterprise Edition
  • Microsoft Visual C++ 5.0 Professional Edition
  • Microsoft Visual C++ 6.0 Professional Edition
  • Microsoft Visual C++, 32-bit Learning Edition 6.0
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Keywords: 
kberrmsg kbprb kbcodegen KB181880
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