Brief introduction
Everything you want to match the string matching method, the function of strong, flexible use of the foundation's focus .
grammar
Ordinary characters
It includes all uppercase and lowercase letters, all numbers, all punctuation and other symbols.
Non-printing characters
| character | description |
| \f | Match a feed character. |
| \n | Matches a newline |
| \r | A carriage return match |
| \s | Matches any whitespace characters, including spaces, tabs, page breaks, and so on. |
| \S | Matches any non-blank character, and \ s opposite |
| \t | Matching tabs. |
| \ v | Matching vertical tab .. |
| \cx | Match control characters specified by the x. |