PCRE2_SUBSTITUTE(3)

NAME
PCRE2 - Perl-compatible regular expressions (revised API)

SYNOPSIS

#include <pcre2.h>

int pcre2_substitute(const pcre2_code *code, PCRE2_SPTR subject,
  PCRE2_SIZE length, PCRE2_SIZE startoffset,
  uint32_t options, pcre2_match_data *match_data,
  pcre2_match_context *mcontext, PCRE2_SPTR replacement,
  PCRE2_SIZE rlength, PCRE2_UCHAR *outputbuffer,
  PCRE2_SIZE *outlengthptr);

DESCRIPTION

This function matches a compiled regular expression against a given subject string, using a matching algorithm that is similar to Perl's. It then makes a copy of the subject, substituting a replacement string for what was matched. Its arguments are:

  code Points to the compiled pattern
  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
  match_data Points to a match data block, or is NULL
  mcontext Points to a match context, or is NULL
  replacement Points to the replacement string
  rlength Length of the replacement string
  outputbuffer Points to the output buffer
  outlengthptr Points to the length of the output buffer

A match context is needed only if you want to:

  Set up a callout function
  Change the limit for calling the internal function match()
  Change the limit for calling match() recursively
  Set custom memory management when the heap is used for recursion

The length, startoffset and rlength values are code units, not characters, as is the contents of the variable pointed at by outlengthptr, which is updated to the actual length of the new string. The options are:

  PCRE2_ANCHORED Match only at the first position
  PCRE2_NOTBOL Subject is not the beginning of a line
  PCRE2_NOTEOL Subject is not the end of a line
  PCRE2_NOTEMPTY An empty string is not a valid match
  PCRE2_NOTEMPTY_ATSTART An empty string at the start of the
                        subject is not a valid match
  PCRE2_NO_UTF_CHECK Do not check the subject or replacement
                        for UTF validity (only relevant if
                        PCRE2_UTF was set at compile time)
  PCRE2_SUBSTITUTE_EXTENDED Do extended replacement processing
  PCRE2_SUBSTITUTE_GLOBAL Replace all occurrences in the subject
  PCRE2_SUBSTITUTE_OVERFLOW_LENGTH If overflow, compute needed length
  PCRE2_SUBSTITUTE_UNKNOWN_UNSET Treat unknown group as unset
  PCRE2_SUBSTITUTE_UNSET_EMPTY Simple unset insert = empty string

The function returns the number of substitutions, which may be zero if there were no matches. The result can be greater than one only when PCRE2_SUBSTITUTE_GLOBAL is set. In the event of an error, a negative error code is returned.

There is a complete description of the PCRE2 native API in the pcre2api page and a description of the POSIX API in the pcre2posix page.