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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                  Match only at end of subject
 PCRE2_NOTBOL                       Subject is not the beginning of a
 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 for UTF validity in
                                     the subject or replacement
                                     (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
 PCRE2_SUBSTITUTE_LITERAL           The replacement string is literal
 PCRE2_SUBSTITUTE_MATCHED           Use pre-existing match data for
                                     first 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-NULL; 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