Python 3 How do I 'declare' an empty `bytes` variable

Question

How do I initialize ('declare') an empty bytes variable in Python 3?

I am trying to receive chunks of bytes, and later change that to a utf-8 string. However, I'm not sure how to initialize the initial variable that will hold the entire series of bytes. This variable is called msg. I can't initialize it as None, because you can't add a bytes and a NoneType. I can't initialize it as a unicode string, because then I will be trying to add bytes to a string. Also, as the receiving program evolves it might get me in to a mess with series of bytes that contain only parts of characters. I can't do without a msg initialization, because then msg would be referenced before assignment. The following is the code in question

def handleClient(conn, addr):     print('Connection from:', addr)     msg = ?     while 1:         chunk = conn.recv(1024)         if not chunk:             break         msg = msg + chunk     msg = str(msg, 'UTF-8')     conn.close()     print('Received:', unpack(msg)) 

Answer 1

Just use an empty byte string, b''.

However, concatenating to a string repeatedly involves copying the string many times. A bytearray, which is mutable, will likely be faster:

msg = bytearray()  # New empty byte array # Append data to the array msg.extend(b"blah") msg.extend(b"foo")  

To decode the byte array to a string, use msg.decode(encoding='utf-8').

Answer 2

Use msg = bytes('', encoding = 'your encoding here').

Encase you want to go with the default encoding, simply use msg = b'', but this will garbage the whole buffer if its not in the same encoding