Find the last added file (boost) - c++

Question

I'm trying to build a function that finds the last added file with a specific extension.
Here's what I did:
void getLastAdded(const fs::path path)
{
const string& ext = ".xml";
fs::path last;
vector<fs::path> files;
fs::recursive_directory_iterator it(path);
fs::recursive_directory_iterator endit;
while (it != endit)
{
if (fs::is_regular_file(*it) && it->path().extension() == ext)
files.push_back(it->path());
++it;
}
for (size_t i = 0; i < files.size(); i++) {
if (i == 0)
last = files[i];
if (fs::last_write_time(last) <= fs::last_write_time(files[i]))
last = files[i];
}
cout << "Last:" << last.filename() << endl;
}
Is there any better way to accomplish this?

Answer 1

Instead of building a (potentially huge) vector of filenames that you won't use/need, I'd filter for the max modification time on-the-fly.
Moreover, don't forget to handle errors:
#include <boost/filesystem.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <iostream>
namespace fs = boost::filesystem;
fs::path getLastAdded(const fs::path path, std::string const& ext = ".xml") {
std::vector<fs::path> files;
namespace pt = boost::posix_time;
pt::ptime max = {pt::neg_infin};
fs::path last;
for (fs::recursive_directory_iterator it(path), endit; it != endit; ++it)
if (fs::is_regular_file(*it) && it->path().extension() == ext)
{
try {
auto stamp = pt::from_time_t(fs::last_write_time(*it));
if (stamp >= max) {
last = *it;
max = stamp;
}
} catch(std::exception const& e) {
std::cerr << "Skipping: " << *it << " (" << e.what() << ")\n";
}
}
return last; // empty if no file matched
}
int main() {
std::cout << "Last: " << getLastAdded(".") << "\n";
}
With some debug information on Coliru:
Live On Coliru
Prints
DEBUG: "./i.xml"
DEBUG: "./z.xml"
DEBUG: "./q.xml"
DEBUG: "./c.xml"
DEBUG: "./v.xml"
DEBUG: "./f.xml"
DEBUG: "./t.xml"
DEBUG: "./d.xml"
DEBUG: "./a.xml"
DEBUG: "./b.xml"
DEBUG: "./e.xml"
DEBUG: "./u.xml"
DEBUG: "./p.xml"
DEBUG: "./g.xml"
DEBUG: "./x.xml"
DEBUG: "./y.xml"
DEBUG: "./j.xml"
DEBUG: "./h.xml"
DEBUG: "./o.xml"
DEBUG: "./m.xml"
DEBUG: "./s.xml"
DEBUG: "./w.xml"
DEBUG: "./l.xml"
DEBUG: "./n.xml"
DEBUG: "./r.xml"
DEBUG: "./k.xml"
Last: "./k.xml"