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Regular Expression
Test String
Substitution
c/c++ file match
Comments
Top Regular Expressions
Url checker with or without http:// or https://
Match string not containing string
Check if a string only contains numbers
Only letters and numbers
Match elements of a url
date format (yyyy-mm-dd)
Url Validation Regex | Regular Expression - Taha
Match an email address
Validate an ip address
nginx test
Extract String Between Two STRINGS
match whole word
Match anything enclosed by square brackets.
Match or Validate phone number
Match html tag
Find Substring within a string that begins and ends with paranthesis
Blocking site with unblocked games
Match dates (M/D/YY, M/D/YYY, MM/DD/YY, MM/DD/YYYY)
Empty String
Match if doesn't start with string
Match string not containing string
Check if a string only contains numbers
Only letters and numbers
Match elements of a url
date format (yyyy-mm-dd)
Url Validation Regex | Regular Expression - Taha
Match an email address
Validate an ip address
nginx test
Extract String Between Two STRINGS
match whole word
Match anything enclosed by square brackets.
Match or Validate phone number
Match html tag
Find Substring within a string that begins and ends with paranthesis
Blocking site with unblocked games
Match dates (M/D/YY, M/D/YYY, MM/DD/YY, MM/DD/YYYY)
Empty String
Match if doesn't start with string
Cheat Sheet
| Character classes | |
|---|---|
| . | any character except newline |
| \w \d \s | word, digit, whitespace |
| \W \D \S | not word, digit, whitespace |
| [abc] | any of a, b, or c |
| [^abc] | not a, b, or c |
| [a-g] | character between a & g |
| Anchors | |
| ^abc$ | start / end of the string |
| \b | word boundary |
| Escaped characters | |
| \. \* \\ | escaped special characters |
| \t \n \r | tab, linefeed, carriage return |
| \u00A9 | unicode escaped © |
| Groups & Lookaround | |
| (abc) | capture group |
| \1 | backreference to group #1 |
| (?:abc) | non-capturing group |
| (?=abc) | positive lookahead |
| (?!abc) | negative lookahead |
| Quantifiers & Alternation | |
| a* a+ a? | 0 or more, 1 or more, 0 or 1 |
| a{5} a{2,} | exactly five, two or more |
| a{1,3} | between one & three |
| a+? a{2,}? | match as few as possible |
| ab|cd | match ab or cd |
