diy2.py

username = "python"
userpassword = "123456"
i=3
while True:
    if i>0:
        name = input("请输入用户名: ")
        userpassword1 = input("请输入密码: ")
        i-=1
        if name == username and password == userpassword:
            print("登录成功!")
            break
        if name != username:
            print("用户名不存在,请重新输入")
            continue
        if userpassword != userpassword1:      
            print("密码错误,请重新输入")
    else:
        print("被锁定")        
        exit()