pcre2_substring_number_from_name - Man Page

#include <pcre2.h>

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

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 pcre2api page and a description of the POSIX API in the pcre2posix page.