C++ - Checking if Internet time is enabled in Win10 - c++

Question

How can I check through C++ code if the Internet Date and Time setting is enabled or not:
Control Panel>"Date and Time">"Set the time and date">"Internet Time">"Change settings…"
This setting:

Answer 1

Here is one of the check methods via WinAPI and the registry.
We will look for HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer values (check https://techlibrary.hpe.com/docs/otlink-wo/How-to-Configure-a-Local-NTP-Server.html for more info).
There is one Enabled value that we are looking for.
So, here is a little non-optimized code with some checks (hope it works...):
#include <iostream>
#include <Windows.h>
bool is_ntp_enabled(void)
{
HKEY key;
const auto sub_key{ TEXT("SYSTEM\\CurrentControlSet\\Services\\W32Time\\TimeProviders\\NtpServer") };
if (ERROR_SUCCESS != RegOpenKeyEx(HKEY_LOCAL_MACHINE, sub_key, NULL, KEY_QUERY_VALUE, &key)) {
std::cerr << "No registry access" << std::endl;
return false;
}
DWORD buff;
const DWORD buff_type{ KEY_READ };
const DWORD buff_size{ sizeof(buff) };
if (ERROR_SUCCESS != RegQueryValueEx(key, TEXT("Enabled"), NULL, (LPDWORD)&buff_type, (LPBYTE)&buff, (LPDWORD)&buff_size)) {
std::cerr << "No registry value access" << std::endl;
return false;
}
if (buff == 0)
return false;
else
return true;
}
int main()
{
std::cout << is_ntp_enabled() << std::endl;
}