int pcre_get_stringnumber(const pcre *code,
const char *name);
This convenience function finds the number of a named substring capturing parenthesis in a compiled pattern. Its 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 PCRE_ERROR_NOSUBSTRING otherwise. When duplicate names are allowed (PCRE_DUPNAMES is set), it is not defined which of the numbers is returned by pcre_get_stringnumber(). You can obtain the complete list by calling pcre_get_stringtable_entries().
There is a complete description of the PCRE native API in the pcreapi page and a description of the POSIX API in the pcreposix page.