I'm trying to send data from python script to D using tcp sockets. As I'm new to D I referred to https://forum.dlang.org/post/lqahvaeqddaddnkhpfyf@forum.dlang.org for client and server code. When I'm sending packed data from python it is of the form

u'\x0f\x10\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\xbaH\x0c\x00'

basically a string! This data is successfully received on the client side in D but when the data is changing to

u'\x0f\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00'

I'm receiving nothing on the client-side in D.
Client code:

void main() {
    import std.socket, std.stdio;
    auto socket = new Socket(AddressFamily.INET,  SocketType.STREAM);
    char[1024] buffer;
    socket.connect(new InternetAddress("127.0.0.1", 10000));
    auto received = socket.receive(buffer); // wait for the server to say hello
    writeln("Server said: ", buffer[0 .. received]);
}

(same code as mentioned in the above link)
Can someone please help me with this?
Also when I'm sending the data in the 1st format, I'm receiving �H as an output on the client, what changes in code should I make so that I receive the data in the same format as sent from Python?

On Thursday, 24 June 2021 at 04:28:45 UTC, Utk wrote:

u'\x0f\x10\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\xbaH\x0c\x00'

u'\x0f\x0c\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00'

void main() {
    import std.socket, std.stdio;
    auto socket = new Socket(AddressFamily.INET,  SocketType.STREAM);
    char[1024] buffer;
    socket.connect(new InternetAddress("127.0.0.1", 10000));
    auto received = socket.receive(buffer); // wait for the server to say hello
    writeln("Server said: ", buffer[0 .. received]);
}

As the buffer's a char[], it's being printed as a string, which
means dumping those raw NUL bytes and such into the terminal, which
is displaying them in a way that's surprising you.

But all of that's working just fine. Change the buffer to ubyte[1024]
and with no other changes you'll get this output:

Server said: [15, 16, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 186, 72, 12, 0]

On Thursday, 24 June 2021 at 05:53:51 UTC, jfondren wrote:

Some alternatives:

Server said: \0f\0c\00\00\00\01\00\00\00\00\00\01\00\00\00\00\00\00\00\00\04\00\00\00\00\00\00\00

from:

ubyte[1024] buffer;
...
writefln("Server said: %(\\%02x%)", buffer[0 .. received]);

Server said: "\x0F\f\0\0\0\x01\0\0\0\0\0\x01\0\0\0\0\0\0\0\0\x04\0\0\0\0\0\0\0"

from:

char[1024] buffer;
...
writefln("Server said: %(%s%)", [buffer[0 .. received]]);

On Thursday, 24 June 2021 at 05:53:51 UTC, jfondren wrote:

Oh, I see! Thanks a lot, will try that.

On Thursday, 24 June 2021 at 06:10:08 UTC, Utk wrote:

For future questions please use the learn forum:

https://forum.dlang.org/group/learn

On Thursday, 24 June 2021 at 07:56:35 UTC, Nicholas Wilson wrote:

Sure!

On Thursday, 24 June 2021 at 04:28:45 UTC, Utk wrote:

That code was assuming you were sending strings which is why it did that.

I wrote a newer version of that socket tutorial btw here:

http://dpldocs.info/this-week-in-d/Blog.Posted_2019_11_11.html

But I again used char there. However, if you just change that to ubyte, you can use the rest of the code for binary data.

(technically, the code works the same way, it is just the write that formats it differently for char vs ubyte when it is displayed, but still ubyte is generally the right thing to do anyway, i probably should have used it even if i am sending hello strings.)

On Thursday, 24 June 2021 at 12:06:30 UTC, Adam D Ruppe wrote: