For the most part if you are writing Windows programs I'd use CreateFile,
ReadFile, and WriteFile (or the Ex versions).  I just wrote this routine
yesterday (uses MFC sorry) to create a temp file name:

CString GetTempFilePath(LPCTSTR strPattern)
{
   CString csPath;
   if(GetTempPath(_MAX_PATH,csPath.GetBuffer(_MAX_PATH+1)) != 0) {
       csPath.ReleaseBuffer();
       CString csTempFile;
       if(GetTempFileName(csPath,strPattern,0,csTempFile.GetBuffer(_MAX_PATH+1))
!= 0) {
           csTempFile.ReleaseBuffer();
           return csTempFile;
       }
   }
   return CString();
}

Using the functions that Will is referring to.  It works pretty well
actually.

Tom

Which one?

Did you try to diagnose the problem looking at errno or strerror()?

Regards,
Will