C++ Parse URL

//sudo apt-get install libboost-all-dev;
//g++ urlregex.cpp -lboost_regex
#include <string>
#include <iostream>
#include <boost/regex.hpp>
 
using std::string;
using std::cout;
using std::endl;
using std::stringstream;
 
void parse_url(const string& url) //with boost
{
    boost::regex ex("(http|https)://([^/ :]+):?([^/ ]*)(/?[^ #?]*)\\x3f?([^ #]*)#?([^ ]*)");
    boost::cmatch what;
    if(regex_match(url.c_str(), what, ex)) 
    {
        string protocol = string(what[1].first, what[1].second);
        string domain   = string(what[2].first, what[2].second);
        string port     = string(what[3].first, what[3].second);
        string path     = string(what[4].first, what[4].second);
        string query    = string(what[5].first, what[5].second);
        cout << "[" << url << "]" << endl;
        cout << protocol << endl;
        cout << domain << endl;
        cout << port << endl;
        cout << path << endl;
        cout << query << endl;
        cout << "-------------------------------" << endl;
    }
}
 
int main(int argc, char* argv[])
{
    parse_url("http://www.google.com");
    parse_url("https://mail.google.com/mail/");
    parse_url("https://www.google.com:443/webhp?gws_rd=ssl");
    return 0;
}

#include <string>
#include <iostream>
 
using std::string;
using std::cout;
using std::endl;
using std::stringstream;
 
string _trim(const string& str)
{
    size_t start = str.find_first_not_of(" \n\r\t");
    size_t until = str.find_last_not_of(" \n\r\t");
    string::const_iterator i = start==string::npos ? str.begin() : str.begin() + start;
    string::const_iterator x = until==string::npos ? str.end()   : str.begin() + until+1;
    return string(i,x);
}
 
void parse_url(const string& raw_url) //no boost
{
    string path,domain,x,protocol,port,query;
    int offset = 0;
    size_t pos1,pos2,pos3,pos4;
    x = _trim(raw_url);
    offset = offset==0 && x.compare(0, 8, "https://")==0 ? 8 : offset;
    offset = offset==0 && x.compare(0, 7, "http://" )==0 ? 7 : offset;
    pos1 = x.find_first_of('/', offset+1 );
    path = pos1==string::npos ? "" : x.substr(pos1);
    domain = string( x.begin()+offset, pos1 != string::npos ? x.begin()+pos1 : x.end() );
    path = (pos2 = path.find("#"))!=string::npos ? path.substr(0,pos2) : path;
    port = (pos3 = domain.find(":"))!=string::npos ? domain.substr(pos3+1) : "";
    domain = domain.substr(0, pos3!=string::npos ? pos3 : domain.length());
    protocol = offset > 0 ? x.substr(0,offset-3) : "";
    query = (pos4 = path.find("?"))!=string::npos ? path.substr(pos4+1) : "";
    path = pos4!=string::npos ? path.substr(0,pos4) : path;
    cout << "[" << raw_url << "]" << endl;
    cout << "protocol: " << protocol << endl;
    cout << "domain: " << domain << endl;
    cout << "port: " << port << endl;
    cout << "path: " << path << endl;
    cout << "query: " << query << endl;
}
 
int main(int argc, char* argv[])
{
    parse_url("http://www.google.com");
    parse_url("https://mail.google.com/mail/");
    parse_url("https://www.google.com:443/webhp?gws_rd=ssl");
    return 0;
}

#include <string>
#include <stdint.h>
#include <cstring>
#include <sstream>
#include <algorithm>
 
#include <iostream> 
using std::cerr; using std::cout; using std::endl;
 
using std::string;
 
class HTTPURL
{
    private:
        string _protocol;// http vs https
        string _domain;  // mail.google.com
        uint16_t _port;  // 80,443
        string _path;    // /mail/
        string _query;   // [after ?] a=b&c=b
 
    public:
        const string &protocol;
        const string &domain;
        const uint16_t &port;
        const string &path;
        const string &query;
 
        HTTPURL(const string& url): protocol(_protocol),domain(_domain),port(_port),path(_path),query(_query)
        {
            string u = _trim(url);
            size_t offset=0, slash_pos, hash_pos, colon_pos, qmark_pos;
            string urlpath,urldomain,urlport;
            uint16_t default_port;
 
            static const char* allowed[] = { "https://", "http://", "ftp://", NULL};
            for(int i=0; allowed[i]!=NULL && this->_protocol.length()==0; i++)
            {
                const char* c=allowed[i];
                if (u.compare(0,strlen(c), c)==0) {
                    offset = strlen(c);
                    this->_protocol=string(c,0,offset-3);
                }
            }
            default_port = this->_protocol=="https" ? 443 : 80;
            slash_pos = u.find_first_of('/', offset+1 );
            urlpath = slash_pos==string::npos ? "/" : u.substr(slash_pos);
            urldomain = string( u.begin()+offset, slash_pos != string::npos ? u.begin()+slash_pos : u.end() );
            urlpath = (hash_pos = urlpath.find("#"))!=string::npos ? urlpath.substr(0,hash_pos) : urlpath;
            urlport = (colon_pos = urldomain.find(":"))!=string::npos ? urldomain.substr(colon_pos+1) : "";
            urldomain = urldomain.substr(0, colon_pos!=string::npos ? colon_pos : urldomain.length());
            this->_domain = _tolower(urldomain);
            this->_query = (qmark_pos = urlpath.find("?"))!=string::npos ? urlpath.substr(qmark_pos+1) : "";
            this->_path = qmark_pos!=string::npos ? urlpath.substr(0,qmark_pos) : urlpath;
            this->_port = urlport.length()==0 ? default_port : _atoi(urlport) ;
        };
    private:
        static inline string _trim(const string& input)
        {
            string str = input;
            size_t endpos = str.find_last_not_of(" \t\n\r");
            if( string::npos != endpos )
            {
                str = str.substr( 0, endpos+1 );
            }
            size_t startpos = str.find_first_not_of(" \t\n\r");
            if( string::npos != startpos )
            {
                str = str.substr( startpos );
            }
            return str;
        };
        static inline string _tolower(const string& input)
        {
            string str = input;
            std::transform(str.begin(), str.end(), str.begin(), ::tolower);
            return str;
        };
        static inline int _atoi(const string& input) 
        {
            int r;
            std::stringstream(input) >> r;
            return r;
        };
};
 
int main(int argc, char **argv)
{
    HTTPURL u("https://Mail.google.com:80/mail/?action=send#action=send");
    cout << "protocol: " << u.protocol << endl;
    cout << "domain: " << u.domain << endl;
    cout << "port: " << u.port << endl;
    cout << "path: " << u.path << endl;
    cout << "query: " << u.query << endl;
    return 0;
}