We write our diaries in code.我们用密码写日记。

If you can't remember your number, write it in code in a diary.如果记不住自己的号码, 那就用代码记在日记簿里吧。

The manuscripts - written in a mysterious code - were a clever hoax.这些手稿是用难以理解的密码写成的, 真是巧妙的花招。