直播内容：
文件操作
user_file = open(‘user_info.txt‘,‘r+‘)
user_file.write(‘\n‘+username)
user_file.close()
2018/6/28
直播课
常用简便编程语句：
1. li = [1,2,3]
li = [x*2 for x in li] #li = [2,4,6]
2. b = True if 1==1 else False --> if 1== 1 :b = True else: b = False
3. li1 = ["name","age"]
li2 = ["pizza",18]
dic3 = dict(zip(li1,li2)) #dic3 = {"name":"pizza","age":18} 将两列表对应成字典
4. open(file, mode)
mode =
‘r‘ open for reading (default)
‘w‘ open for writing, truncating the file first
‘x‘ create a new file and open it for writing
‘a‘ open for writing, appending to the end of the file if it exists
‘b‘ binary mode
‘t‘ text mode (default)
‘+‘ open a disk file for updating (reading and writing)
‘U‘ universal newline mode (deprecated)
The default mode is ‘rt‘ (open for reading text). For binary random
access, the mode ‘w+b‘ opens and truncates the file to 0 bytes, while
‘r+b‘ opens the file without truncation. The ‘x‘ mode implies ‘w‘ and
raises an `FileExistsError` if the file already exists.
路飞学城 - python7天集训 - 直播课
原文：https://www.cnblogs.com/cantin-python-notes/p/9242591.html
