def login(): i = 1 while i <= 3: username = input("输入用户名：") password = input("输入密码：") with open("a.txt") as f: for line in f.readlines(): user = line.strip().split() if user[0] == username and user[1] == password: print("登录成功！") return print("用户名或密码错误！") i += 1 print("账号锁定！") login()代码优化

可以将文件读取和用户验证分开处理，将用户验证的部分封装成一个函数，并添加参数来传递用户名和密码。同时，可以将错误提示信息统一处理，并在登录失败时增加一定时间的等待，以防止暴力破解。下面是代码优化后的示例：

import time

def read_user_info():
    with open("a.txt") as f:
        users = [line.strip().split() for line in f.readlines()]
    return users

def validate_user(users, username, password):
    for user in users:
        if user[0] == username and user[1] == password:
            return True
    return False

def login():
    i = 1
    users = read_user_info()
    while i <= 3:
        username = input("输入用户名：")
        password = input("输入密码：")
        if validate_user(users, username, password):
            print("登录成功！")
            return
        else:
            print("用户名或密码错误！")
            if i < 3:
                print("请稍等片刻再尝试。")
            time.sleep(1)
            i += 1
    print("账号锁定！")

login()