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Editor to share with you how to use regular expressions in php, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's learn about it!

Atoms:

^ take the reverse in () or [] for example: [^\ d] equals matching non-numbers

Amurz Amurz Z0-9 / / the most common characters

(abc) / / those expanded in parentheses will be treated as a whole match, and the abc must be in one block at the same time in order to match successfully.

[abc] / / Square brackets are the opposite of parentheses, indicating that they can be a, b, c

\ d contains all numbers [0-9]

\ B except for all numbers [^ 0-9]

\ w contains all common characters [a-zA-Z_0-9]

\ w does not contain all common characters [^ a-zA-Z_0-9]

\ s contains blank areas, such as carriage return, line feeds, paging, etc. [\ f\ n\ r]

Metacharacters:

* match 0 times one or more times of the previous content for example: / key*rey/ matches y 0 times one or more times y * is a whole, regardless of whether there is y in the actual string; {"keyrey", "kerey": match successfully}

. Matches content 0 times one or more times, but does not include carriage return line feeds, wildcard characters; / key.*rey/ matches anything in the middle of key rey {keyfds*$7fd732f_) rey: match succeeded}

+ match one or more times of the previous content / key+rey/ matches one or more times of y. Y is required in the string to match successfully; {"keyrey", "keyyyyyrey": match success}, {"kerey": match failure}

? Match 0 times or 1 time of the previous content / key?rey/ 0 times or once of y; {"keyrey"kerey": match succeeded}, {"keyyrey": match failed}

| | Select match similar to PHP | | / keyrey | baidu/ {"keyrey%*baidu": match successfully}, {"fdas", "baidu": match success} |

^ matches the first part of the string / ^ keyrey/ must start with keyrey

The end of the matching string / keyrey$/ must end with $

\ b match word boundaries, which can be spaces or special characters mainly used to match spaces in Chinese context

\ B match content except with word boundaries

{m} match the previous content repeated to m times; / key {1} rey/ match y1 times {"keyrey": match succeeded}, {"keyyrey", "kerey": match failed}

{m,} match the repetition of the previous content m to n times; / key {1,} rey/ match 1 to n times {"keyrey", "keyyyyrey": success, "kerey": match failure}

The number of repetitions of the previous content is m to n / key {3 ~ 5} rey/ matches between 3 and 6 times.

() merge the overall match and put it into memory, you can use\ 1\ 2. Get / (gle) (. *)\\ 1.*\ 2 / {"gleAAAgle11AAA": successful}

Common pattern modifiers in PHP:

Operation priority: () *? + {} ^ $\ b | finally in the order of operation

I regular content is case-insensitive when matching (default is case-sensitive)

M uses multi-line recognition matching when matching the first or last content.

S cancels the escape carriage return to a single-line match such as. When playing the Standard PvP match

X ignore whitespace in the rule

A forces a match from scratch

D know each other $matching tail does not have any content\ n

U forbids greedy matching to trace only to the nearest match and ends, and is often used in regular expressions on collection programs.

Non-greed in java (. *?)

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