Regular Expression Pocket Reference, 2nd Edition

Pattern-Matching Functions

PHP provides several standalone functions for pattern matching. When creating regular expression strings, you need to escape embedded backslashes; otherwise, the backslash is interpreted in the string before being sent to the regular expression engine.

array preg_grep (stringpattern, arrayinput)

Return array containing every element of input matched by pattern.

int preg_match_all (stringpattern, stringsubject, arraymatches [, intflags])

Search for all matches of pattern against subject, and return the number of matches. The matched substrings are placed in the matches array. The first element of matches is an array containing the text of each full match. Each additional element n of matches is an array containing the nth capture group match for each full match. So, for example, matches[7][3] contains the text matches by the seventh capture group in the fourth match of pattern in subject.

The default ordering of matches can be set explicitly with the PREG_SET_ORDER flag. PREG_SET_ORDER sets a more intuitive ordering, where each element of matches is an array corresponding to a match. Element 0 of each array is the complete match, and each additional element corresponds to a capture group. The additional flag PREG_OFFSET_CAPTURE causes each array element containing a string to be replaced with a two-element array containing the same string and starting character position in subject.

int preg_match (stringpattern, stringsubject [, arraymatches [, intflags]])

Return ...