python学习之路：文件with自动关闭+字符转码

with语句可实现文件的自动关闭功能：

 1 import sys
 2 ‘‘‘
 3 with open("yesterday2","r",encoding="utf-8") as f: #自动关闭并释放文件资源
 4     for line in f:
 5         print(line)
 6 ‘‘‘
 7 with open("yesterday2","r",encoding="utf-8") as f, 8      open("yesterday2","r",encoding="utf-8") as f2:
 9     for line in f:
10         print(line)

字符转码：https://www.cnblogs.com/jxzheng/p/5186490.html

https://www.cnblogs.com/nulige/p/6063999.html

 1 s ="你好" #默认Unicode
 2 s_to_GBK =s.encode("GBK") #Unicode转码成gbk
 3 print(s_to_GBK)
 4
 5 print(s_to_GBK.decode("GBK")) #从GBK转码成unicode
 6
 7 print(s.encode("GBK"))
 8 print(s.encode("utf-8"))
 9 print(s.encode("utf-8").decode("utf-8").encode("gb2312"))
10
11 import sys
12 print(sys.getdefaultencoding()) #取系统默认encoding