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Direct File manipulation

Posted on 2002-04-05
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Last Modified: 2010-04-02
Hello,
   I need to search directly for different records within a file in its actual location...as basically as possible.  Does anyone have any suggestions for me?
Thanks
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Question by:pingle
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5 Comments
 
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Expert Comment

by:jkr
ID: 6921176
See http://support.microsoft.com/support/kb/articles/Q292/4/85.ASP ('HOWTO: Programmatically Save an HTML Page to Disk'). The scoop is:

Accomplishing this task from a Visual C++ host is very straightforward. You can use an IWebBrowser2
interface to call the QueryInterface method for the IHTMLDocument2 interface. After you obtain a pointer
to the document, then call QueryInterface for the IPersistFile interface. After you obtain this interface
pointer, you can call the save method to save the file to disk.

   HRESULT          hr    = E_FAIL;
   IDispatch*       pDisp = NULL;
   IHTMLDocument2*  pDoc  = NULL;
   
   pDisp                  = m_webOC.GetDocument();

  if(SUCCEEDED(hr = pDisp->QueryInterface(IID_IHTMLDocument2,(void**)&pDoc)))
  {
      IPersistFile*     pFile     =     NULL;
      if(SUCCEEDED(pDoc->QueryInterface(IID_IPersistFile,(void**)&pFile)))
      {
    LPCOLESTR     file = L"c:\\test1.htm";
    pFile->Save(file,TRUE);
      }
  }
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LVL 86

Expert Comment

by:jkr
ID: 6921178
Ooops, sorry, wrong browser window :o)
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LVL 86

Accepted Solution

by:
jkr earned 50 total points
ID: 6921188
Well, the easiest way for navigating a file is using 'fseek()':


#include <stdio.h>

void main( void )
{
   FILE *stream;
   char line[81];
   int  result;

   stream = fopen( "fseek.out", "w+" );
   if( stream == NULL )
      printf( "The file fseek.out was not opened\n" );
   else
   {
      fprintf( stream, "The fseek begins here: "
                       "This is the file 'fseek.out'.\n" );
      result = fseek( stream, 23L, SEEK_SET);
      if( result )
         perror( "Fseek failed" );
      else
      {
         printf( "File pointer is set to middle of first line.\n" );
         fgets( line, 80, stream );
         printf( "%s", line );

      }
      fclose( stream );
   }
}

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LVL 30

Expert Comment

by:Axter
ID: 6921320
If you're running on a Windows platform, you can do a MapView, and get a (void*) pointer to the data in the file.
You can then use regular C++ functions to manipulation the data in the file.
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LVL 30

Expert Comment

by:Axter
ID: 6921337
FYI:
You can also do MapView from unix using mmap and munmap functions.
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