It's not frequent I come across a need for a regex but when I do, I often find myself forgetting what specific parts may mean. Here's a little cheatsheet I made myself ~ perhaps there's some value for you.
| Symbol | Name | Meaning |
|---|---|---|
. | Wildcard | Anything can take this guy's place. You'll need to escape (\.) it for periods. |
\d | Digit | Will search for any digit. It's sister, \D is for any non-digit. Ex: \d\d\d looks for 3 digits. |
[ ] | 'Only' | Anything inside braces will search through things only containing characters inside. If you were to negate this ^, you'll ignore those characters. Ex: [^abc] Looks for 3 characters not starting with a, b, or c |
{ } | Repeating | Will look for the proceeding group for the number of times inside. [wxy]{3} |
* | Any Number | Looks for any number of the proceeding group |
+ | At least | Looks for at least one of the proceeding group |
? | Optional | Will treat the prior group as an optional match. ab?c will match abc or ac |
\s | Whitespace | Space, newline, tab, carriage return |
^ $ | 'Block' | Using these anchors, we can prevent getting matches encased inside words. ex: ^Mission: successful$ |
( ) | Capture | If you want to extract a specific piece of information about your matches, you'll wrap it with parentheses. You can nest these as much as you'd like, spitting out each group. |
pipe | OR | yep. Markdown tables are fun. The OR (same representation as bitwise OR) applies. |