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

 int pcre2_substring_number_from_name(const pcre2_code *code,  " PCRE2_SPTR name);" 

. .rs This convenience function finds the number of a named substring capturing parenthesis in a compiled pattern, provided that it is a unique name. The function arguments are: code Compiled regular expression name Name whose number is required The yield of the function is the number of the parenthesis if the name is found, or PCRE2_ERROR_NOSUBSTRING if it is not found. When duplicate names are allowed (PCRE2_DUPNAMES is set), if the name is not unique, PCRE2_ERROR_NOUNIQUESUBSTRING is returned. You can obtain the list of numbers with the same name by calling pcre2_substring_nametable_scan().

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.