PCRE2 - Perl-compatible regular expressions (revised API)
#include <pcre2.h>
void pcre2_substring_free(PCRE2_UCHAR *buffer);
This is a convenience function for freeing the memory obtained by a previous call to pcre2_substring_get_byname() or pcre2_substring_get_bynumber(). Its only argument is a pointer to the string. If the argument is NULL, the function does nothing.
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.