Trolltech Home | Qt-interest Home | Recent Threads | All Threads | Author | Date
All threads index page 1

Qt-interest Archive, September 2002
A problem about network programming with QT and standard C

• Subject: A problem about network programming with QT and standard C
• From: qiliang@xxxxxxxxxxxxx
• Date: Tue, 3 Sep 2002 16:43:40 +0800
• Sender: qiliang@xxxxxxxxxx
• To: qt-interest@xxxxxxxxxxxxx

Recently I use QT and standard C to program a network C/S.

I use standard C to program a server, and use qt to program a client.

When I transfer the file from server to client, it's good.


in server the code is:

if( ( fp = fopen( "./test.tar.gz", "r" ) ) == NULL )
{
    exit(0);
}
else
{
    while( !feof( fp ) )
    {
        len = fread( str, sizeof(char), MAXLINE, fp );
        if( send( new_fd, str, len, 0 ) == -1 )
        {
             close( new_fd );
             exit(0);
        }
    }
}

in client the code is:

     char str[MAXLINE];
     QString sTemp;
     int len;
     bool sign = TRUE;

     sTemp = "test.tar.gz";

     QFile file( sTemp );
    if ( file.open( IO_Raw | IO_WriteOnly ) == false )
    {
        return;
    }

    QDataStream ds( &file );

     while ( sign )
     {
         len = m_pSsocket->readBlock( str, MAXLINE );
          if ( (len == 0) || (len == -1) )
          {
               sign = FALSE;
          }
          else
          {
               ds.writeRawBytes( str, len );
          }
     }

     ds.unsetDevice();
     file.close();

But when I transfer the file from client to server, it has a mistake. The
file which the server received is shorter than the file which the client
sent. The difference less than 4096 bytes. It means:

Length1 ( the length of the file in client ) - Length2 ( the length of the
file in server ) < 4096

in server the code is:

if( ( fp = fopen( "./sth.txt", "w" ) ) ==NULL )
{
    exit(0);
}
else
{
    sign = 1;
    which( sign )
    {
        if( ( len = recv( new_fd, str, MAXLINE, 0 ) ) == -1 )
        {
            close( new_fd );
            exit(0);
        }
        if( len == 0  )
        {
            sign = 0;
        }
        else
        {
            fwrite( str, sizeof(char), len, fp );
        }
    }
}

in client the code is:

    QFile file( "sth.txt" );
    if ( file.open( IO_Raw | IO_ReadOnly ) == false )
    {
        return;
    }

     QDataStream sth( &file );
     char str[MAXLINE];
     int i, step, len;

     step = file.size() / MAXLINE;

     for ( i = 0; i < step; ++i )
     {
          sth.readRawBytes( str, MAXLINE );
          m_pSsocket->writeBlock( str, MAXLINE );
     }

     len = file.size() - MAXLINE * step;
     sth.readRawBytes( str, len );
     m_pSsocket->writeBlock( str, len );

     sth.unsetDevice();
     file.close();

Could you help me? Thanks in advance.

Best regards,

Qi Liang