PCRE - Perl-compatible regular expressions .rs #include <pcre.h>

 int pcre_get_substring(const char *subject, int *ovector,  " int stringcount, int stringnumber,"  " const char **stringptr);"  int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,  " int stringcount, int stringnumber,"  " PCRE_SPTR16 *stringptr);"  int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,  " int stringcount, int stringnumber,"  " PCRE_SPTR32 *stringptr);" 

. .rs This is a convenience function for extracting a captured substring. The arguments are: subject Subject that has been successfully matched ovector Offset vector that pcre[16|32]_exec() used stringcount Value returned by pcre[16|32]_exec() stringnumber Number of the required substring stringptr Where to put the string pointer The memory in which the substring is placed is obtained by calling pcre[16|32]_malloc(). The convenience function pcre[16|32]_free_substring() can be used to free it when it is no longer needed. The yield of the function is the length of the substring, PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or PCRE_ERROR_NOSUBSTRING if the string number is invalid.

There is a complete description of the PCRE native API in the HREF
pcreapi
page and a description of the POSIX API in the HREF
pcreposix
page.