Useful site for writing and testing regex - https://www.regexpal.com/ - https://regex101.com/ - http://regextutorials.com/index.html - https://regexper.com/#%5E%28%5Ba-z%5D%2B%5Cd*_%5Ba-z%5Cd_%5D*%7C_%2B%5Ba-z%5Cd%5D%2B%5Ba-z%5Cd_%5D*%29%24 ![[image_1626507098408_0.png]] Image Source: https://twitter.com/manekinekko/status/1335330878403260419 | code | Purpose | | :-----------------: | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: | | `\d` | represent any digit 0-9 | | `[0-9]` or `[abc]` | matches a range or any specfic item in the brackets could find a,b, or c but will find all of them | | `\D` | match any NON-digit characters | | `[^0-9]` or `[^\d]` | says match all BUT these in which case this is digits | | `\w` | will match words, `\D` will match white space, punctuation, hyphens, etc. while `\w` does not. `\w` matches only letters and numbers, equivalently: `[a-zA-Z0-9]` | | `\W` | to match a non word character. matches opposite of alphanumeric and is equivalent to `[^_a-zA-Z0-9]` | | `\s` | match a space character | | `\n` | New line | | `\t` | a tab | | `\r` | carriage return | | `.` | match any single character | | `\b` | boundry, so for a word `\bA.{5}T\b` the boundries encompass words that start with 'A', end with 'T' and have 5 characters in the middle like ANCYENT or ANCIENT also akin to `\b\w{7}\b` | | `^` | beginning of a line anchor | | ` | end of a line anchor | | | the pipe is an 'or' statement in brackets is saying 't' OR 'T' in a regex search | | `[0-3[4-5]]` | Union of 2 character sets, this would return 04, 05, 14, 15, 24, 25, 34, 35, this can also work with negation to use a set of 'NOT THESE' characters | --- | Quantifier | Description | | | ---------- | :---------------------------------------------------------------------------------------------------------------------------------: | --- | | `{8}` | quantifyer, same as linux CLI `.{8}` would match any 8 characters, this one matches the patter a specific number of times, 8 times. | | | `{8,}` | the comma means it will match or more occurances of the pattern | | | `{2,4}` | will match the pattern anytime it ocurs 2-4 times any of those options are captured | |