dhwh.py

username = "python"
userpasword = "123456"
while True:
    name = input("请输入用户名:")
    password = input("请输入密码:")
    if name == username and password == userpasword:
        print("登陆成功")
        break
    if name != username:
        print("用户名不存在")
        continue
    if password != userpasword:
        print("密码错误，请重新输入")
print("欢迎来到贝尔编程!")