Download a URL in C++

Question

I want to be able to download a URL in C++. Something as simple as:

std::string s;
s=download("http://www.example.com/myfile.html");

Ideally, this would include URLs like:

• ftp://example.com/myfile.dat
• file:///usr/home/myfile.dat
• https://example.com/myfile.html

I was using asio in Boost, but it didn't really seem to have the code for handling protocols like ftp and https. Now I discovered QT has more what I need (http://doc.trolltech.com/2.3/network.html).

It's tempting to make the switch to Qt, but it seems a bit heavy and intersects a lot of Boost functionality. Is it worth learning yet another API (Qt) or can Boost do more than I think?

Answer 1

You can use URLDownloadToFile.

#include <Urlmon.h>
    HANDLE hr;
    hr=URLDownloadToFile(NULL, L"http://www.example.com/myfile.html",L"mylocalfile.html",BINDF_GETNEWESTVERSION,NULL);

According to MSDN, BINDF_GETNEWESTVERSION - is a "Value that indicates that the bind operation retrieves the newest version of the data or object available. In URL monikers, this flag maps to the WinInet flag, INTERNET_FLAG_RELOAD, which forces a download of the requested resource".