On Sun, Jun 5, 2011 at 12:55 PM, David Nadlinger <see@klickverbot.at> wrote:

On 6/5/11 9:49 PM, Jonathan Sternberg wrote:

Cool. It compiles, but it doesn't seem to be doing exactly what I want. Say I send
2 integers from the server to the client. When I do this on the client, it seems
to do the wrong thing.

int first, second;
auto sock = new TcpSocket();
sock.connect(new InternetAddress("localhost", 10000));

writeln( sock.receive((&first)[0..int.sizeof]) );
writeln( sock.receive((&second)[0..int.sizeof] );

This seems to print 8 and then block on the second call to receive. I thought that
D was supposed to recognize that the array was only 4 bytes long and read only
that much. (note: on a 32-bit machine, so int comes out to 4 bytes)

When I do:

writeln( (&first)[0..int.sizeof].length );

It prints 4 as it's supposed to.

&first is of type int*, so (&first)[0..int.sizeof] returns a slice pointing to int.sizeof (i.e. 4) ints, not a single one as you intend to. Just use ť(&first)[0..1]Ť as per my original reply, and you should be fine.

Also, note that receive is basically a direct call to C's receive, which means that it has the same behavior with regards to buffer filling. Calling sock.receive((&first)[0..1]) returns the number of bytes read, which may be less than 4. I've handled this in the past by writing a template function that takes a primitive type and loops until it has read all the bytes it needs.

Oh, and D's int is always 32 bits, on 32 bit or 64 bit platforms. size_t is an alias that switches from uint on 32 bit to ulong on 64 bit, and there's another alias somewhere for signed types (ssize_t, I believe). The primitive types always have the same sizes until you get into things like cent.