TypeError: a bytes-like object is required, not 'str' when writing to a file

Question

import socket

def Main():
    host = '127.0.0.1'
    port = 5001

    server = ('127.0.0.1',5000)

    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.bind((host, port))

    message = input("-> ")
    while message != 'q':
        s.sendto (message, server)
        data, addr = s.recvfrom(1024)
        print ('Received from server: ' + (data))
        message = input("-> ")
    s.close()

if __name__ == '__main__':
    Main()

When I run this code the line s.sendto (message, server) causes a TypeError: a bytes-like object is required, not 'str'.

How do you fix this kind of problem? I tried searching the internet but can't find a solution.

Possible duplicate of How do I encode a string to bytes in the send method of a socket connection in one line? — scraaappy
– scraaappy, Commented Aug 16, 2018 at 15:53
@scraaappy that's not a good duplicate target; all the answers suggest prepending b to a string, but in this case the string is coming from user input, so prepending isn't possible. Explicitly encoding is better anyway - prepending b won't work if the string contains non-ascii characters. — snakecharmerb
– snakecharmerb, Commented Aug 17, 2018 at 4:49

blue note · Accepted Answer · 2018-08-17 17:19:41Z

5

Sockets read and write bytes, not strings (that's a property of sockets in general, not a python-specific implementaiton choice). That's the reason for the error.

Strings have an encode() methods that transforms them to byte-objects. So, instead of writing my_text, write my_text.encode() to your socket.

Similarly, when you read for the socket, you get a bytes-like object, on which you can call input_message.decode() to convert it into string

edited Aug 17, 2018 at 17:19

answered Aug 16, 2018 at 15:50

blue note

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2 Comments

Firaga Over a year ago

Thank you for your help i did what you said and it solve the problem

blue note Over a year ago

@Firaga: thanks, please accept answer if it solves the problem

Michael · Accepted Answer · 2020-08-18 10:43:13Z

1

The error is due to the fact you are not encoding the message. Just change:

c.sendto(message, server)

to

c.sendto(message.encode(), server)

in your code.

Example:

    import  socket
    
    s=socket.socket()
    port=12345
    s.bind(('',port))
    print("Socket bind succesfully")
    s.listen(5)
    // note this point 
    message="This is message send to client "
    
    while True:
        c,addr=s.accept()
        // here is error occured 
        c.send(message)
        c.close()

This is will result in an error message:

    c.send(message)
    TypeError: a bytes-like object is required, not 'str'

and in order to fix it, we need to change:

c.send(message)

to

c.send(message.encode())

edited Aug 18, 2020 at 10:43

Michael

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answered Aug 18, 2020 at 7:50

AJAY KACHHIYAPATEL

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