You can brute force it and unfortunately, the so-called Caesar cipher is not very secure because if you assume, for our purposes in English alphabet with 26 characters, say all lowercase for all uppercase, my God, you only have to try like 24, 25, 26 possible rotations until you can figure out what his secret message is.

你可以强行解密但是不幸地是，所谓的凯撒密码不是很安全的,因为如果假设，对于我们的26个字符的字母表,指明所有的小写为大写，我的天，你只要试24，25次，26次就可以解答出,密文的内容。

哈佛公开课 - 计算机科学课程节选

s2 So, I'm passing in the first character in s2, I'm making it uppercase and then I'm putting it back so casually speaking this is just capitalizing the first letter of whatever word the user typed in to s2.

那么，我把第一个字符传递给，我把它转换成大写的，然后存下来,简单说，这就是把用户输入s2中的单词,的第一个字母转换成大写的。

哈佛公开课 - 计算机科学课程节选