Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

PREG constants

Constants	Description	As of
PREG_PATTERN_ORDER	Orders results so that $matches[0] is an array of full pattern matches, $matches[1] is an array of strings matched by the first parenthesized subpattern, and so on. This flag is only used with preg_match_all().
PREG_SET_ORDER	Orders results so that $matches[0] is an array of first set of matches, $matches[1] is an array of second set of matches, and so on. This flag is only used with preg_match_all().
PREG_OFFSET_CAPTURE	See the description of PREG_SPLIT_OFFSET_CAPTURE.
PREG_SPLIT_NO_EMPTY	This flag tells preg_split() to return only non-empty pieces.
PREG_SPLIT_DELIM_CAPTURE	This flag tells preg_split() to capture parenthesized expression in the delimiter pattern as well.
PREG_SPLIT_OFFSET_CAPTURE	If this flag is set, for every occurring match the appendant string offset will also be returned. Note that this changes the return values in an array where every element is an array consisting of the matched string at offset 0 and its string offset within subject at offset 1. This flag is only used for preg_split().
PREG_UNMATCHED_AS_NULL	This flag tells preg_match() and preg_match_all() to include unmatched subpatterns in $matches as NULL values. Without this flag, unmatched subpatterns are reported as empty strings, as if they were empty matches. Setting this flag allows to distinguish between these two cases.	7.2.0
PREG_NO_ERROR	Returned by preg_last_error() if there were no errors.	5.2.0
PREG_INTERNAL_ERROR	Returned by preg_last_error() if there was an internal PCRE error.	5.2.0
PREG_BACKTRACK_LIMIT_ERROR	Returned by preg_last_error() if backtrack limit was exhausted.	5.2.0
PREG_RECURSION_LIMIT_ERROR	Returned by preg_last_error() if recursion limit was exhausted.	5.2.0
PREG_BAD_UTF8_ERROR	Returned by preg_last_error() if the last error was caused by malformed UTF-8 data (only when running a regex in UTF-8 mode).	5.2.0
PREG_BAD_UTF8_OFFSET_ERROR	Returned by preg_last_error() if the offset didn't correspond to the begin of a valid UTF-8 code point (only when running a regex in UTF-8 mode).	5.3.0
PREG_JIT_STACKLIMIT_ERROR	Returned by preg_last_error() if the last PCRE function failed due to limited JIT stack space.	7.0.0
PCRE_VERSION	PCRE version and release date (e.g. "7.0 18-Dec-2006").	5.2.4