pcre2_substring_get_byname man page
PCRE2 — Perl-compatible regular expressions (revised API)
int pcre2_substring_get_byname(pcre2_match_data *match_data, PCRE2_SPTR name, PCRE2_UCHAR **bufferptr, PCRE2_SIZE *bufflen);
This is a convenience function for extracting a captured substring by name into newly acquired memory. The arguments are:
match_data The match data for the match
name Name of the required substring
bufferptr Where to put the string pointer
bufflen Where to put the string length
The memory in which the substring is placed is obtained by calling the same memory allocation function that was used for the match data block. The convenience function pcre2_substring_free() can be used to free it when it is no longer needed. The yield of the function is zero for success or one of the following error numbers:
PCRE2_ERROR_NOSUBSTRING there are no groups of that name
PCRE2_ERROR_UNAVAILBLE the ovector was too small for that group
PCRE2_ERROR_UNSET the group did not participate in the match
PCRE2_ERROR_NOMEMORY memory could not be obtained
If there is more than one group with the given name, the first one that is set is returned. In this situation PCRE2_ERROR_UNSET means that no group with the given name was set.
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.