pcre_exec specification

# pcre_exec man page

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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.

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