pcre2/doc/pcre2_substitute.3

.TH PCRE2_SUBSTITUTE 3 "22 January 2020" "PCRE2 10.35"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.SH SYNOPSIS
.rs
.sp
.B #include <pcre2.h>
.PP
.nf
.B int pcre2_substitute(const pcre2_code *\fIcode\fP, PCRE2_SPTR \fIsubject\fP,
.B "  PCRE2_SIZE \fIlength\fP, PCRE2_SIZE \fIstartoffset\fP,"
.B "  uint32_t \fIoptions\fP, pcre2_match_data *\fImatch_data\fP,"
.B "  pcre2_match_context *\fImcontext\fP, PCRE2_SPTR \fIreplacement\fP,"
.B "  PCRE2_SIZE \fIrlength\fP, PCRE2_UCHAR *\fIoutputbuffer\fP,"
.B "  PCRE2_SIZE *\fIoutlengthptr\fP);"
.fi
.
.SH DESCRIPTION
.rs
.sp
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:
.sp
  \fIcode\fP          Points to the compiled pattern
  \fIsubject\fP       Points to the subject string
  \fIlength\fP        Length of the subject string
  \fIstartoffset\fP   Offset in the subject at which to start matching
  \fIoptions\fP       Option bits
  \fImatch_data\fP    Points to a match data block, or is NULL
  \fImcontext\fP      Points to a match context, or is NULL
  \fIreplacement\fP   Points to the replacement string
  \fIrlength\fP       Length of the replacement string
  \fIoutputbuffer\fP  Points to the output buffer
  \fIoutlengthptr\fP  Points to the length of the output buffer
.sp
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:
.sp
  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
.sp
The \fIlength\fP, \fIstartoffset\fP and \fIrlength\fP values are code units,
not characters, as is the contents of the variable pointed at by
\fIoutlengthptr\fP. 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.
.P
The subject and replacement lengths can be given as PCRE2_ZERO_TERMINATED for
zero-terminated strings. The options are:
.sp
  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
.\" JOIN
  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
.\" JOIN
  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
.sp
If PCRE2_SUBSTITUTE_LITERAL is set, PCRE2_SUBSTITUTE_EXTENDED,
PCRE2_SUBSTITUTE_UNKNOWN_UNSET, and PCRE2_SUBSTITUTE_UNSET_EMPTY are ignored.
.P
If PCRE2_SUBSTITUTE_MATCHED is set, \fImatch_data\fP must be non-zero; its
contents must be the result of a call to \fBpcre2_match()\fP using the same
pattern and subject.
.P
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.
.P
There is a complete description of the PCRE2 native API in the
.\" HREF
\fBpcre2api\fP
.\"
page and a description of the POSIX API in the
.\" HREF
\fBpcre2posix\fP
.\"
page.