Enter a valid user id and password.

输入有效用户ID和密码。

youdao

Customer logs in with a valid user id and password.

客户使用有效用户ID和密码登录。

youdao

Server user '% s' is not a valid user in database' % s'.

服务器用户“% s”不是数据库“% s”中的有效用户。

youdao

But when you start writing programs, especially when we get to web-based stuff where you want -- to check the user's input -- is it valid, is it an email address, -- and all these different scenarios -- it's actually often useful to be able to just enumerate them or rattle them off using this switching construct instead.

但是当你看是写程序时，特别是当我们,使用基于网络的东西，你想要,检查用户的输入-,它是合法的吗？它是不是一个电子邮箱地址？,所有的这些场景-,实际上它常常是有用的，当你用枚举结构列举它们,或者用它来快速地来说出它们。

哈佛公开课 - 计算机科学课程节选

Some of the programs have different requirements for what constitutes a valid user name or an adequate password, creating the disadvantage of multiple credentials for a single human resources hub.

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