Copy a remote file

[robertfoley]

Hi there,
I was wondering if any of you gurus can help me with this. I am new to C++ and am developing on MicroSoft Visual Studio 2003 (Visual C++).
I am trying to simply read a file from a webserver and save it locally. My code works when I copy the file from a local location but throws a null pointer when I give the url of the file.

+++++++++++++++++++++++++++++++++++++++++++++++
FILE* fp1 = fopen("http://192.100.53.90/DimensionView/booking_info.txt","r");
FILE* fp2 = fopen("C:\\booking_info.txt","w");

while(!feof(fp1)) {
char mystring[100];
fgets(mystring, 100, fp1);
//fputs(fp2,*mystring,strlen(*mystring));
fputs(mystring, fp2);
}
fclose (fp1);
fclose (fp2);
++++++++++++++++++++++++++++++++++++++++++++++++

Is it that fopen is can only be used to obtain a pointer to local files only? I have searched and searched but cannot find how to read a remote file (rfopen? )

Any help would be great.

Thanks,
Rob

[redhead]

fopen() can only be used for local files, it dosn't know anything about connections through network layer.
In order to retrieve a file through the network, you will need to open a socket to the apropriate server, decide if that times out which means no connection, if it dosn't, then send a file_exist request through the socket, if thats a success you can open/fetch the file.
This however requires alot more code, than your fopen() call.

[QUantumAnenome]

I would like to learn how to do this also. Is there a tutorial or sample code that shows how to do this? Thanks.

[redhead]

I havn't got time right now to come up with an example, but tomorrow I'll work on one.. Perhaps this item would prove to be a tutorial in the future..

[DJMaze]

I use this simple code in windows

#include <wininet.h>
#pragma link "lib/wininet.lib"

CString contents;
bool getwebdata(TCHAR *server, unsigned short port, TCHAR *uri) {
  HINTERNET hINet, hConnection, hData;
  char buffer[256];
  DWORD dwRead;

  hINet = InternetOpen(_T("Mozilla/1.0"), INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
  if ( !hINet ) {
    return false;
  }
  try {
    hConnection = InternetConnect(hINet, server, port, _T(" "),_T(" "), INTERNET_SERVICE_HTTP, 0, 0);
    if ( !hConnection ) {
      InternetCloseHandle(hINet);
      return false;
    }

    // Get data
    hData = HttpOpenRequest(hConnection, "GET", uri, NULL, NULL, NULL,
            INTERNET_FLAG_KEEP_CONNECTION | INTERNET_FLAG_NO_CACHE_WRITE | INTERNET_FLAG_RELOAD, 0);
    if ( !hData ) {
      InternetCloseHandle(hConnection);
      InternetCloseHandle(hINet);
      return false;
    }

    HttpSendRequest( hData, NULL, 0, NULL, 0);
    while( InternetReadFile(hData, buffer, 255, &dwRead) ) {
      if ( dwRead == 0 ) break;
      buffer[dwRead] = 0;
      contents += buffer;
    }
  }
  catch( ... ) {
    ShowMessage("Error sending/receiving data from internet");
//    e->ReportError();
//    e->Delete();
  }

  InternetCloseHandle(hConnection);
  InternetCloseHandle(hINet);
  InternetCloseHandle(hData);

  return true;
}

Donno if it works properly in VS2k3 but it gives you a rough idea how to use the Windows wininet library if your app is for use in Win OS

[webcomplete.com]

Thats MFC not standard C++ though.

Anyways I got example for Java (not javascript) should you want one too.

[webcomplete.com]

eh sorry - i thought this was standard c++

[Valmont]

It was in the standard C++ forum, but I moved it.

[DJMaze]

Originally Posted by webcomplete.com

Thats MFC not standard C++ though.

Originally Posted by robertfoley

I am new to C++ and am developing on MicroSoft Visual Studio 2003 (Visual C++).

It's not MFC specific, since you can use the wininet.dll any way you want.
Shure you can write your own fsockopen() or something but robert says he's a newbie and it does take a lot more work and POSIX works completely different anyway.
So i thought the above code might help him.

[QUantumAnenome]

Thanks DJMaze! I finally got something working w/ MSVS 2003.

For some reason, HttpOpenRequest() HttpSendRequest() pair wasn't working, so after poking around the docs found InternetOpenUrl().

The big hurdle for me was not knowing this set of functions even existed, so I now have a whole new world to explore!

BTW, I found libwww on the w3c.org website, finally got their samples to work, and your method is WAY more simple and clean.

Anyone who wants my simple MFC based app based on DJMaze's code snippet is welcome to email me for it.