PCRE2 - Perl-compatible regular expressions (revised API) .rs #include <pcre2.h>

 int pcre2_substring_copy_bynumber(pcre2_match_data *match_data,  " uint32_t number, PCRE2_UCHAR *buffer,"  " PCRE2_SIZE *bufflen);" 

. .rs This is a convenience function for extracting a captured substring into a given buffer. The arguments are: match_data The match data block for the match number Number of the required substring buffer Buffer to receive the string bufflen Length of buffer The bufflen variable is updated with the length of the extracted string, excluding the terminating zero. 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 number 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 the buffer is too small

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