小案例：编写登录接口

 1 #Author BigD
 2 import os,sys
 3 
 4 i=0
 5 while i<3:
 6     username = input("enter your name:")
 7 
 8     #检查用户是否存在
 9     locked_lines = open("locked.txt","r+")　　　　　##对文件进行读写
10     for locked_line in locked_lines:
11         if username == locked_line.strip(‘\n‘):　　##取得姓名
12             print ("you are locked,fuck off")
13             sys.exit(0)
14 
15 
16     lines = open("user-passwd.txt","r")　　　　　　 ##对文件只读
17     for line in lines:
18         [name,passwd] = line.strip(‘\n‘).split(‘ ‘,1)    ##取得姓名和密码。strip 去除两边的符号，spilt分隔
19 
20         if username == name:
21             print("hello,%s"%(name))
22 
23             j=0
24             while j<3:
25                 print(passwd)
26                 pd = input("enter your passwrod:")
27                 if pd == passwd:
28                     print("welcome %s"%(name))
29                     exit(0)
30                 else:
31                     print("wrong!you have %d times"%(2-j))
32 
33                 j += 1
34             else:
35                 locked_lines.write(username + ‘\n‘)
36                 print("locked")
37                 exit(0)
38 
39         else:
40             pass　　　　　　　　　　　　
41 
42     else:
43         print("you have %d times"%(2-i))
44     i += 1
45 else:
46     print ("user is not exist.bye!")