#!/usr/bin/env python
# -*- coding:utf-8 -*-
count = 0
flag = 0
#提示用户需要做什么操作
option = int(input("提示：数字1为注册用户，数字2为登录系统，请选择:"))

if option == 1:
    user = input("请输入用户名：")
    passwd = input("请输入密码：")
    f = open("user.txt","a")
    f.write("%s:%s\n" % (user,passwd))
    f.close()
elif option == 2:
    while count < 3:
        user = input("请输入登录名：")
        passwd = input("请输入密码：")
        UserPassList = [i.strip() for i in open(‘user.txt‘,‘r‘).readlines()]  #按行读取文件内容，并去空格。
        for i in UserPassList:
            username = i.split(‘:‘)[0]
            paasword = i.split(‘:‘)[1]
            if user == username and passwd == paasword:
                flag = 1
                break
        if flag == 1:
            break
        else:
            count += 1
    if flag == 1:
         print("登录成功")
    else:
         print("登录失败")
else:
    print("输入错误，SX")

1.python语言实现用户登录程序