in case

in case
in case 以防假使，如果
用作连词 (conj.)
Write the telephone number down in case you forget.
把电话号码写下来以免忘了。
In case that he leaves, please inform me.
如果他离开，请通知我。
In case you need something, please don't hesitate to let me know.
如果你需要什么东西，请不客气地对我说。

详解：

in case后跟句子，而in case of后加名词（短语），如：
We have an auxiliary generator in case of power cuts.
我们有一台万一断电时使用的备用发电机。

in order that<-->lest