The South Carolina Governor asked Lamon to give Lincoln this message: "Nothing can prevent war except a decision by the President of the United States to accept the secession of the South.

VOA: special.2009.08.06

Ah ha, it goes into that accept portion, prints out a message, and goes back around the while loop to say try again. And it's going to keep doing this until I give it something that does serve as a float.

他会说输入一个浮点数，啊哈，它就到了那段处理代码,打印出消息,然后回到while循环让我们再输一次,它会持续这么做直到它接受到一个浮点数。

麻省理工公开课 - 计算机科学及编程导论课程节选