diy2.py

i=3-
username = "python"
userpassword = "123456"
while True:
    if i >0:
        name = input("请输入用户名:")
        password = input("请输入密码:")
        i=i-1
        if name == username and password == userpassword:
            print("登录成功!")
            break
        if n!=username:
            print("账号不存在")
        if password !=username
        continue
            print("密码错误")
        print("用户名和密码错误!请重新输入")
    else:
        print("用户未锁定")
print("欢迎来到贝尔编程!")