Another thing to consider -
auto t1 = std::chrono::system_clock::now();
std::this_thread::sleep_for(std::chrono::seconds(5));
auto t2 = std::chrono::system_clock::now();
auto d = t2 - t1;
auto s = std::chrono::duration_cast<std::chrono::seconds>(d);
auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(d);
std::cout << "Seconds " << s.count() << ", milliseconds " << ms.count() << std::endl;
CStringW strw_s(std::to_wstring(s.count()).c_str());
CStringW strw_ms(std::to_wstring(ms.count()).c_str());
CStringA stra_s(std::to_string(s.count()).c_str());
CStringA stra_ms(std::to_string(ms.count()).c_str());
printf_s("Seconds(ansi): %s, milliseconds(ansi): %s\n", (LPCSTR) stra_s, (LPCSTR) stra_ms);
wprintf_s(L"Seconds(UNICODE): %s, milliseconds(UNICODE): %s\n", (LPCWSTR)strw_s, (LPCWSTR)strw_ms);