If I'm iterating from I on the outside, I on the inside, I'm going to start changing the value and I might very well induce an infinite loop but J is okay.

如果我在外面从I开始迭代，或从里面开始迭代，我将开始改变它的值,我可能引起一个无限循环，但是用J是可以的。

哈佛公开课 - 计算机科学课程节选