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how to Trim the url in c++.

new1 (47)
Hello,


I got stuck in trim the url to header host format in c++.

Here i have string or char * type url as below
<code>
http://www.cplusplus.com/user/
</code>

I want to reduce to cplusplus.com as my final string. i did it as much as i can but i thought it was not a proper way to trim.

Any help would be appreciated.
Last edited on
new1 (47)
here i tried , but i don't think this is the best way to do this.

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string str ("http://www.cplusplus.com/user/");
char *ptr ,*st = NULL;

        ptr = strchr( (char *) str.c_str(), ':');  
        cout<< ptr <<endl;                        //  ://   ......
        ptr++;
        cout<< ptr << endl;                      //   // .....
        while (*ptr == '/') {
                if(*(ptr+1) == '/') {
                        ptr = strchr( (char*) str.c_str(), '/');    
                        cout<<ptr <<endl;         //   / ....
                }
                ++ptr;
        }
        cout<< ptr << endl;           //  ......
new1 (47)
Got it ..using string find with substr ..so easily
cire (8284)
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// http://ideone.com/4DkTyb
#include <iostream>
#include <regex>
#include <string>

std::string extract_authority(std::string uri)
{
    // See: Apendix B from http://www.ietf.org/rfc/rfc2396.txt for regular expression
    std::regex uri_exp(R"xxx(^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?)xxx");
    std::smatch matches;

    if (std::regex_match(uri, matches, uri_exp) && matches.size() >= 5)
        return matches[4].str();

    return std::string();
}

std::string trim_prefix(std::string s, std::string prefix)
{
    return s.find(prefix) == 0 ? s.substr(prefix.length()) : s;
}

int main()
{
    std::vector<std::string> examples =
    {
        R"(http://www.ics.uci.edu/pub/ietf/uri/#Related)",
        R"(http://www.cplusplus.com/user/)",
        R"(ftp://ftp.is.co.za/rfc/rfc1808.txt)",
        R"(gopher://spinaltap.micro.umn.edu/00/Weather/California/Los%20Angeles")",
        R"(http://www.math.uio.no/faq/compression-faq/part1.html)",
        R"(mailto:mduerst@ifi.unizh.ch)",
        R"(news:comp.infosystems.www.servers.unix")",
        R"(telnet://melvyl.ucop.edu/)",
    };

    for (auto example : examples)
    {
        auto auth = extract_authority(example);

        std::cout << '"' << trim_prefix(auth, "www.") << "\" (" << example << ")\n";
    }
}
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