导入模块

from lib.username import f
f()
import sys
for i in sys.path:
    print(i)

在当前目录开始查找， lib文件夹下面有一个username.py导入具体的函数

hello
H:\python17\wang
C:\Users\Administrator\AppData\Local\Programs\Python\Python35\python35.zip
C:\Users\Administrator\AppData\Local\Programs\Python\Python35\DLLs
C:\Users\Administrator\AppData\Local\Programs\Python\Python35\lib
C:\Users\Administrator\AppData\Local\Programs\Python\Python35
C:\Users\Administrator\AppData\Local\Programs\Python\Python35\lib\site-packages

from lib  import username
username.f()
import sys
for i in sys.path:
    print(i)

另外一种方式导入
import lib.username 
lib.username.f()
系统自带的的，直接import导入，
自定义import
第三方
进行安装
C:\Users\Administrator\AppData\Local\Programs\Python\Python35\lib\site-packages

from lib import username as bbb 
bbb.f()#别名
以后尽量用from ，而import功能单一的

通过hash算法加密登陆

#!/usr/bin/env python3
import hashlib
def md5(s1):
    hash = hashlib.md5(bytes("dkfskf", encoding="utf-8"))
    hash.update(bytes(s1, encoding="utf-8"))
    return  hash.hexdigest()
def regester(user,pwd):
    with open('db','a',encoding="utf-8") as f:
       temp = user + "|" + md5(pwd)
       f.write(temp)

def login(username,pwd):
    with open('db','r',encoding="utf-8") as f:
        for line in f:
           u,p = line.strip().split("|")
           if u == username and p == md5(pwd):
               return True
           return False
t = input("1、登陆 2、注册 ：")
if t == '2' :
    user = input("Username:")
    pwd  = input("pasword:")
    regester(user,pwd)
elif t == '1':
    user = input("Username:")
    pwd  = input("pasword:")
    m = login(user,pwd)
    if m:
        print("登陆成功")
    else:
        print("登陆失败")

 

import os
t = os.path.exists('./lib/commons')#判断当前文件夹是否存在
print(t)