pcre_exec (3) - Linux Manuals

pcre_exec: Perl-compatible regular expressions

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.