Basic Regex Cheat Sheet

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May 31, 2017 PHP No Comments

Symbols. — (period) Matches any single character, except for line breaks.

* — Matches the preceding expression 0 or more times.

+ — Matches the preceding expression 1 or more times.

? — Preceding expression is optional (Matches 0 or 1 times).

^ — Matches the beginning of the string.

$ — Matches the end of the string.

Character groups

\d — Matches any single digit character.

\w — Matches any word character (alphanumeric & underscore).

[XYZ] — Character Set: Matches any single character from the character within the brackets. You can also do a range such as [A-Z]

[XYZ]+ — Matches one or more of any of the characters in the set.

[^A-Z] — Inside a character set, the ^ is used for negation. In this example, match anything that is NOT an uppercase letter.

Flags:

There are five optional flags. They can be used separately or together and are placed after the closing slash. Example: /[A-Z]/g I’ll only be introducing 2 here.

g — Global search

i — case insensitive search

Advanced

(x) — Capturing Parenthesis: Matches x and remembers it so we can use it later.

(?:x) — Non-capturing Parenthesis: Matches x and does not remembers it.

x(?=y) — Lookahead: Matches x only if it is followed by y.

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