how to send an array over socket and then get each item in python

Question

Below is my server.py and client.py. So I want to print each item in the array separated by a new line. Server.py:

import socket

listener = socket.socket()
listener.bind(("",12345))
listener.listen()

while 1:
    conn = listener.accept()
    sock = conn[0]

    encoded_message = sock.recv(2048)
    while len(encoded_message) > 0:
    message += encoded_message.decode() + "\n"
    encoded_message = sock.recv(2048)

print(message)

encoded_message = message.encode()
sock.send(encoded_message)
sock.shutdown(1)

sock.close()

client.py:

import socket

sock = socket.socket()
sock.connect(("localhost",12345))

testing_strings = ["A123 45",
               "L65 78",
               "E486",
               "D4 1 0",
               "E1.0",
               "S1.0",
               "S0 2 -945 1689 -950 230 -25 1 -1e-15",
               "Not a number",
               "S0 2 -945 1689 -950 230 -25 1 0",
               "S0 2 -945 1689 -950 230 G 1 1e-15"]

for c in testing_strings:
    encoded_message = c.encode()
    sock.send(encoded_message)

sock.shutdown(1)

encoded_message = sock.recv(2048)
while len(encoded_message) > 0:
    message += encoded_message.decode()
    encoded_message = sock.recv(2048)

print(message)
sock.close()

But I always get

A123 45L65 78E486D4 1 0
E1.0
S1.0
S0 2 -945 1689 -950 230 -25 1 -1e-15
Not a number
S0 2 -945 1689 -950 230 -25 1 0
S0 2 -945 1689 -950 230 G 1 1e-15

It seems like the first three items always go together and the rest works just fine. I want to separate them out and print each line. I would appreciate any help. Thanks. Expected output:

A123 45
L65 78
E486
D4 1 0
E1.0
S1.0
S0 2 -945 1689 -950 230 -25 1 -1e-15
Not a number
S0 2 -945 1689 -950 230 -25 1 0
S0 2 -945 1689 -950 230 G 1 1e-15

post the final expected output

RomanPerekhrest
– RomanPerekhrest

2017-10-27 18:19:32 +00:00
Commented Oct 27, 2017 at 18:19 — RomanPerekhrest
– RomanPerekhrest, Commented Oct 27, 2017 at 18:19
I just edited it. Thanks

Lucy
– Lucy

2017-10-27 18:25:38 +00:00
Commented Oct 27, 2017 at 18:25 — Lucy
– Lucy, Commented Oct 27, 2017 at 18:25
can you show how are running your both scripts?

RomanPerekhrest
– RomanPerekhrest

2017-10-27 19:14:11 +00:00
Commented Oct 27, 2017 at 19:14 — RomanPerekhrest
– RomanPerekhrest, Commented Oct 27, 2017 at 19:14

klassmann · Accepted Answer · 2017-10-27 18:43:02Z

1

How each piece of message doesn't have the same size, so I think that the best way to accomplish this is some structured communication using serialization like XML, JSON, etc.

If you don't want use serialization, you can use a start and end tag or unique symbol, like a pipe "|", for each time you send the data. So, in the server code, you should concatenate all message and finally split the final content into a list.

separator = "|".encode()
for c in testing_strings:
    encoded_message = c.encode()
    sock.send(separator)
    sock.send(encoded_message)

I wrote an answer to a similar question, you can see here:

Simple Python Server Client File Transfer

I hope it helps you.

answered Oct 27, 2017 at 18:43

klassmann

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1 Comment

Lucy Over a year ago

Hey it works. Thanks a lot. Actually I'm trying to pass each item in the array to calculate the polynomials. And I was testing to see how the data come in.Now I know it works fine. Thanks

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