"salsipius" <salsipius@salsipius.com> wrote in message
news:1129050397.033095.182650@g47g2000cwa.googlegr oups.com...[color=blue]
> Hi all thanks in advance for reading. I am writing a serial port app
> with the help of many examples and I am not quite clear on how to get
> the data back from the method call?[/color]
From looking at the code below, I see two possible pieces
of information you can receive from the 'ReadData()' function:
the type 'int' value it returns (representing the actual
number of bytes read), and the data stored at the address
represented by the parameter 'buffer'.
[color=blue]
> I have pasted the read method
> below, it takes a void * as the buffer. I know I need to send something
> by reference[/color]
No you don't (you could, but there's no reason to).
[color=blue]
> but am unclear on how to do it.[/color]
Allocate sufficient storage to represent whatever data the
function stores there, and pass its address as the 'buffer'
parameter.
[color=blue]
>
> What I want it the buffer to be a string that I can use or manipulte.[/color]
Well, the 'ReadFile()' function appears to store data
at address 'buffer'. I don't know if it places a string
terminator at the end of the data or not. There's no
'ReadFile()' function in standard C++, so you'll need
to look up its documentation to see how to use it and
what it does. (If you want the data at 'buffer' to be
a string, and ReadFile doesn't terminate it with a zero,
just allocate an additional byte in your storage, and
put it there yourself. Hint: the 'bytes read' return value
will tell you where to put it.)
[color=blue]
> Can anyone help Please?[/color]
Not with the nonstandard function, not here.
The 'Hungarian notation' makes this stuff look like
Windows, if so try a Windows newsgroup, website
(e.g.
www.msdn.microsoft.com), or mailing list.
-Mike
[color=blue]
>
> int MBSerial::ReadData( void *buffer, int limit )
> {
>
> if( !m_bOpened || m_hIDComDev == NULL ) return( 0 );
>
> BOOL bReadStatus;
> DWORD dwBytesRead, dwErrorFlags;
> COMSTAT ComStat;
>
> ClearCommError( m_hIDComDev, &dwErrorFlags, &ComStat );
> if( !ComStat.cbInQue ) return( 0 );
>
> dwBytesRead = (DWORD) ComStat.cbInQue;
> if( limit < (int) dwBytesRead ) dwBytesRead = (DWORD) limit;
>
> bReadStatus = ReadFile( m_hIDComDev, &buffer, dwBytesRead,
> &dwBytesRead, &m_OverlappedRead );
> if( !bReadStatus ){
> if( GetLastError() == ERROR_IO_PENDING ){
> WaitForSingleObject( m_OverlappedRead.hEvent, 2000 );
> return( (int) dwBytesRead );
> }
> return( 0 );
> }
> return( (int) dwBytesRead );
> }
>[/color]
Help with ReadFile() 
