ipv4 sockaddr to human readable ip

ipv4_sockaddr_to_human_readable_ip.cpp

#include <netdb.h>
#include <arpa/inet.h>
#include <iostream>
#include <cstring>
#include <stdexcept>

int main(int argc, char* argv[]) {
	if (argc < 2) {
		return 0;
	}
	const std::string host { argv[1] };
	addrinfo hints { };
	memset(&hints, 0, sizeof(addrinfo));
	hints.ai_family = PF_UNSPEC;
	hints.ai_flags = AI_ADDRCONFIG;
	hints.ai_socktype = SOCK_STREAM;
	addrinfo* ainfo;
	int s = getaddrinfo(host.c_str(), NULL, &hints, &ainfo);
	if (s) {
		throw std::runtime_error(std::string(gai_strerror(s)) + " " + host);
	}
	char str[128];
	inet_ntop(AF_INET, &(((sockaddr_in *) ainfo->ai_addr)->sin_addr), (char*) &str, sizeof(str));
	std::cerr << host << " -> " << str << "\n";
}