pcre2_substitute - Man Page

Perl-compatible regular expressions (revised API)


#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);


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 data block is needed only if you want to inspect the data from the final match that is returned in that block or if PCRE2_SUBSTITUTE_MATCHED is set. A match context is needed only if you want to:

 Set up a callout function
 Set a matching offset limit
 Change the backtracking match limit
 Change the backtracking depth limit
 Set custom memory management in the match context

The length, startoffset and rlength values are code units, not characters, as is the contents of the variable pointed at by outlengthptr. This variable must contain the length of the output buffer when the function is called. If the function is successful, the value is changed to the length of the new string, excluding the trailing zero that is automatically added.

The subject and replacement lengths can be given as PCRE2_ZERO_TERMINATED for zero-terminated strings. The options are:

 PCRE2_ANCHORED             Match only at the first position
 PCRE2_ENDANCHORED          Pattern can match only at end of subject
 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_JIT               Do not use JIT matching
 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_LITERAL   The replacement string is literal
 PCRE2_SUBSTITUTE_MATCHED   Use pre-existing match data for 1st match
 PCRE2_SUBSTITUTE_OVERFLOW_LENGTH  If overflow, compute needed length
 PCRE2_SUBSTITUTE_REPLACEMENT_ONLY  Return only replacement string(s)
 PCRE2_SUBSTITUTE_UNKNOWN_UNSET  Treat unknown group as unset
 PCRE2_SUBSTITUTE_UNSET_EMPTY  Simple unset insert = empty string


If PCRE2_SUBSTITUTE_MATCHED is set, match_data must be non-zero; its contents must be the result of a call to pcre2_match() using the same pattern and subject.

The function returns the number of substitutions, which may be zero if there are no matches. The result may 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.


22 January 2020 PCRE2 10.35