NAME

PCRE - Perl-compatible regular expressions

SYNOPSIS

#include <pcre.h>

int pcre_exec(const pcre *code, const pcre_extra *extra,
     const char *subject, int length, int startoffset,
     int options, int *ovector, int ovecsize);

int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
     PCRE_SPTR16 subject, int length, int startoffset,
     int options, int *ovector, int ovecsize);

int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
     PCRE_SPTR32 subject, int length, int startoffset,
     int options, int *ovector, int ovecsize);

DESCRIPTION

This function matches a compiled regular expression against a given subject string, using a matching algorithm that is similar to Perl's. It returns offsets to captured substrings. Its arguments are:

code Points to the compiled pattern
extra Points to an associated pcre[16|32]_extra structure,
or is NULL
subject Points to the subject string
length Length of the subject string
startoffset Offset in the subject at which to start matching
options Option bits
ovector Points to a vector of ints for result offsets
ovecsize Number of elements in the vector (a multiple of 3)

The units for length and startoffset are bytes for pcre_exec(), 16-bit data items for pcre16_exec(), and 32-bit items for pcre32_exec(). The options are:

PCRE_ANCHORED Match only at the first position
PCRE_BSR_ANYCRLF \R matches only CR, LF, or CRLF
PCRE_BSR_UNICODE \R matches all Unicode line endings
PCRE_NEWLINE_ANY Recognize any Unicode newline sequence
PCRE_NEWLINE_ANYCRLF Recognize CR, LF, & CRLF as newline sequences
PCRE_NEWLINE_CR Recognize CR as the only newline sequence
PCRE_NEWLINE_CRLF Recognize CRLF as the only newline sequence
PCRE_NEWLINE_LF Recognize LF as the only newline sequence
PCRE_NOTBOL Subject string is not the beginning of a line
PCRE_NOTEOL Subject string is not the end of a line
PCRE_NOTEMPTY An empty string is not a valid match
PCRE_NOTEMPTY_ATSTART An empty string at the start of the subject
is not a valid match
PCRE_NO_START_OPTIMIZE Do not do "start-match" optimizations
PCRE_NO_UTF16_CHECK Do not check the subject for UTF-16
validity (only relevant if PCRE_UTF16
was set at compile time)
PCRE_NO_UTF32_CHECK Do not check the subject for UTF-32
validity (only relevant if PCRE_UTF32
was set at compile time)
PCRE_NO_UTF8_CHECK Do not check the subject for UTF-8
validity (only relevant if PCRE_UTF8
was set at compile time)
PCRE_PARTIAL ) Return PCRE_ERROR_PARTIAL for a partial
PCRE_PARTIAL_SOFT ) match if no full matches are found
PCRE_PARTIAL_HARD Return PCRE_ERROR_PARTIAL for a partial match
if that is found before a full match

For details of partial matching, see the pcrepartial page. A pcre_extra structure contains the following fields:

flags Bits indicating which fields are set
study_data Opaque data from pcre[16|32]_study()
match_limit Limit on internal resource use
match_limit_recursion Limit on internal recursion depth
callout_data Opaque data passed back to callouts
tables Points to character tables or is NULL
mark For passing back a *MARK pointer
executable_jit Opaque data from JIT compilation

The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT, PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA, PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT.

There is a complete description of the PCRE native API in the pcreapi page and a description of the POSIX API in the pcreposix page.