If you know you're not gonna output a full string %C but a single character, percent C will get that job done.

如果你不想输出一个完整的字符串,而是输出一个字母，就要用到。

哈佛公开课 - 计算机科学课程节选

S We saw percent S which is a placeholder for a string, turns out as you'll see over time there are other placeholders.

我们知道字符串占位符，输出来就是另一番场景了,还有一些其他类型的占位符。

哈佛公开课 - 计算机科学课程节选

But the string, the sentence or the words that we're displaying on the screen, previously you clicked on a little white text field and typed it in, well now you're gonna do the same thing at the keyboard but you're gonna have to sandwich it in between double quotation marks.

这些你想输出到屏幕上的字符串啊，语句啊,单词啊，或者你事先,在白色输入框中敲进去的内容，现在你们需要用键盘做同样的事情,但是你们要写在,双引号之间。

哈佛公开课 - 计算机科学课程节选