regex
| Character | Explain |
|---|---|
. | any char |
* | 0 or more times |
+ | 1 or more times |
? | optional char |
{m, n} | repeat m to n times |
\d | Any Digit |
\w | matches any single letter, number or underscore (same as [a-zA-Z0-9_]) |
\s | white space |
() | back-references (or capturing groups), stored in variable |