KB181880 - PRB: "Access to an Unnamed File Was Denied" Error

Article ID: 181880

Article Last Modified on 12/8/2003

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++ 6.0 Standard Edition

This article was previously published under Q181880

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.

Additional query words: kbvc400 kbvc500 kbvc600

Keywords: kberrmsg kbprb kbcodegen KB181880