Reading a textfile on the web

[lozenge]

A text file is hosted on the internet. www.a.com/b.txt

I want to read the file for input. How do I do this?

[benjamin d]

C++ does not have a built-in way of using the HTTP protocol. You'll want a HTTP library for that:

http://scumways.com/happyhttp/happyhttp.html
http://curl.haxx.se/libcurl/competitors.html

I haven't used any HTTP library yet, so I'm afraid I can't recommend or assist you in learning one. But the HappyHTTP library appears to be the simplest to use. (Site mentions it does not currently compile in Visual Studio.)

[Cubbi]

The most portable approach (which will likely become part of C++ in the next standard extension), is boost.asio

#include <iostream>
#include <string>
#include <boost/asio.hpp>
int main()
{
    boost::asio::ip::tcp::iostream s("www.a.com", "http");
    if(!s)
        std::cout << "Could not connect to www.a.com\n";
    s  << "GET /b.txt HTTP/1.0\r\n"
       << "Host: www.a.com\r\n"
       << "Accept: */*\r\n"
       << "Connection: close\r\n\r\n" ;
    for(std::string line; getline(s, line); )
         std::cout << line << '\n';
}

As you can see, it is a bit more low-level than you probably need (you have to write HTTP protocol by hand). If that's not what you want, do try out third-party HTTP libraries:
curl++: http://curlpp.org/
poco: http://pocoproject.org/
cpp-netlib: http://cpp-netlib.sourceforge.net/