#include <iostream>
#include <string>
 
std::string get_str_between_two_str(std::string s, std::string start_delim,
		std::string stop_delim)
{
	unsigned first_delim_pos = s.find(start_delim);
	unsigned end_pos_of_first_delim = first_delim_pos + start_delim.length();
	unsigned last_delim_pos = s.find(stop_delim);
 
	return s.substr(end_pos_of_first_delim,
			last_delim_pos - end_pos_of_first_delim);
}
 
int main() {
    // Want to extract _0_192.168.1.18_
	std::string s = "_STARTDELIMITER_0_192.168.1.18_STOPDELIMITER_";
	std::string s2 = "ABC123_STARTDELIMITER_0_192.168.1.18_STOPDELIMITER_XYZ345";
 
	std::string start_delim = "_STARTDELIMITER";
	std::string stop_delim = "STOPDELIMITER_";
 
	std::cout << get_str_between_two_str(s, start_delim, stop_delim) << std::endl;
	std::cout << get_str_between_two_str(s2, start_delim, stop_delim) << std::endl;
 
	return 0;
}

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