PHP Regular Expressions (PCRE)

PHP Regular Expressions (PCRE)

The regular expression (regular expression) describes a pattern of string matching that can be used to check whether a string contains a seed string, replaces a matched substring, or extracts a substring that matches a certain condition from a string.

For more regular expressions, refer to our: Regular Expressions-tutorials.

In PHP we can use the PCRE extension to match the pattern of strings.

PCRE function

function	Description
Preg_filter	Perform a regular expression search and replace
Preg_grep	Returns an array entry for the matching pattern
Preg_last_error	Returns the error code generated by the last Pcre regular execution
Preg_match_all	Performs a global regular expression match
Preg_match	Performs a regular expression match
Preg_quote	Escaping regular expression characters
Preg_replace_callback_array	Performs a regular expression search and replaces it with a callback
Preg_replace_callback	Performs a regular expression search and replaces it with a callback
Preg_replace	Perform a search and replace of a regular expression
Preg_split	Separating strings with a regular expression

Preg Constants From

Constants	Description	which version
PREG_PATTERN_ORDER	The results are sorted according to "rules", only for Preg_match_all (), i.e. $matches[0] is the matching result of the complete rule, $matches [1] is the result of the first subgroup match, and so on.	Since
PREG_SET_ORDER	The results are sorted by "set" and used only for Preg_match_all (), or $matches[0] to hold all the results of the first match (including subgroups) information, $matches [1] to save the second result information, and so on.
PREG_OFFSET_CAPTURE	View PREG_SPLIT_OFFSET_CAPTURE the description.	4.3.0
PREG_SPLIT_NO_EMPTY	This tag tells Preg_split () to return to the non-empty part.
PREG_SPLIT_DELIM_CAPTURE	This tag tells Preg_split () to capture what the parentheses expression matches.	4.0.5
PREG_SPLIT_OFFSET_CAPTURE	If this flag is set, the offset of each occurrence of the matched substring is returned. Note that this changes the values in the returned array, each element is represented by the matching substring as the No. 0 element, and it is relative to the target string offset as an array of the 1th elements. This tag can only be used for preg_split ().	4.3.0
PREG_NO_ERROR	Call Preg_last_error () returns when there is no matching error.	5.2.0
PREG_INTERNAL_ERROR	If there is an pcre internal error, call Preg_last_error () is returned.	5.2.0
PREG_BACKTRACK_LIMIT_ERROR	If the call backtracking limit is exceeded, the call to Preg_last_error () is returned.	5.2.0
PREG_RECURSION_LIMIT_ERROR	If the recursion limit is exceeded, the call to Preg_last_error () is returned.	5.2.0
PREG_BAD_UTF8_ERROR	If the last error is due to the exception of the Utf-8 data (only available under run in UTF-8 mode regular expressions). Causes the call to Preg_last_error () to return.	5.2.0
PREG_BAD_UTF8_OFFSET_ERROR	If the offset does not match the valid Urf-8 code (only available under run in UTF-8 mode regular expression). Call Preg_last_error () to return.	5.3.0
PCRE_VERSION	Pcre version number and release date (for example: "7.0 18-dec-2006").	5.2.4

PHP Regular Expressions (PCRE)