字符串长度-错误的结果？

Question

I can't understand what is wrong with the following code:

System.out.println("TEST:"+"/index/index/(\\d+)/".length());

Output: TEST:19 . But as I see there must be 20. Where is my mistake?

Answer 1

In java, \\ is an escape character.

So: The \\\\ is actually a single \\ .

And therefore that part of the string reads like this: (\\d+) , which as per regex definition means "1 or more digits" :)