NameError: name 'buf' is not defined

Question

# This is a sample Python script.

# Press Shift+F10 to execute it or replace it with your code.
# Press Double Shift to search everywhere for classes, files, tool windows, actions, and settings.
import socket
import time
import multiprocessing
import threading

b=1
global buf



def data_accept():
    global buf
    # IPV4,TCP协议
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    # 绑定ip和端口，bind接受的是一个元组
    sock.bind(('127.0.0.1', 6010))
    # 设置监听，其值阻塞队列长度，一共可以有5+1个客户端和服务器连接
    sock.listen(5)
    # 等待客户段请求
    connection, address = sock.accept()
    a = [1, 2, 3, 4]
    while True:
        buf = connection.recv(40960)


def main():
    global buf
    thread_data = threading.Thread(target=data_accept)
    thread_data.start()
    while True:
        print(":", float(buf.decode('utf-8')))


if __name__ == '__main__':
    main()

Answer 1

No need to use the global keyword when initializing the variable. Just use buf, for example, buf = None

import socket
import time
import multiprocessing
import threading

b=1
buf = None

def data_accept():
    global buf
    # IPV4,TCP??
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    # ??ip????bind????????
    sock.bind(('127.0.0.1', 6010))
    # ???????????????????5+1??????????
    sock.listen(5)
    # ???????
    connection, address = sock.accept()
    a = [1, 2, 3, 4]
    while True:
        buf = connection.recv(40960)
        print('asdf')


def main():
    global buf
    thread_data = threading.Thread(target=data_accept)
    thread_data.start()
    while True:
        if buf is not None:
            print(":", float(buf.decode('utf-8')))


if __name__ == '__main__':
    main()