[ILUG] Serial Port

[Justin Mason]

"Kenn Humborg" said:

> > char a_string[15] = "today is april ";
> > int date = 11;
> > sprintf(outgoing_msg,"%s %d",a_string,date);
> > bytes_written = write(serial_port_fd,outgoing_msg,255);
> > outgoing_msg isn't 255 long but is padded with zeros;
> 
> Don't send a bunch of zeros unnecessarily.  Write the
> correct number of bytes:
> 
>    char a_string[15] = "today is april ";
>    int date = 11;
>    int bytes_to_write;
>    bytes_to_write = sprintf(outgoing_msg,"%s %d",a_string,date);
>    bytes_written = write(serial_port_fd,outgoing_msg,bytes_to_write);

Agreed!

BTW, you'd be fine using this on Linux, but on some other UNIXes sprintf()
returns slightly wierd values, so using snprintf() would be better for
portability wherever it's available.

Actually in general terms snprintf() is better full stop, as sprintf()
is vulnerable to buffer overflows. So if the outgoing_msg buffer is 255
bytes long, use:

     bytes_to_write = snprintf(outgoing_msg,255,"%s %d",a_string,date);

--j.