diy5.py

username = "python"
userpassword = "123456"
while True:
    name = input("请输入用户名:")
    password = input("请输入密码:")
    if name == username and password == userpassword:
        print("登录成功!")
        break
    if  name != username:
         print("账号错误")
         continue
    if password == userpassword:
         print("密码错误")
print("欢迎来到贝尔编程!")