Returns a matched substring from a regex handle. Substring ids start at 0 and end at captures-1, where captures is the number returned by MatchRegex.
bool GetRegexSubString(Handle regex, int str_id, char buffer, int maxlen)
The regex handle to extract data from.
The index of the expression to get - starts at 0, and ends at captures - 1.
The buffer to set to the matching substring.
The maximum string length of the buffer.
True if a substring was found, False on fail/error
str_id = 0 is the full captured string, anything else is the capture group index.