title: Convert current time from windows to unix timestamp in C or C++
body: <p>First off, I know that this question was asked quite some times (although it seems that 90% are about converting Unix ts -> Windows).
  Secondly, I would add a comment to another accepted question where my problem would fit in instead of adding another one but I don't have enough reputation.</p>
  
  <p>I saw the accepted solution in <a href="https://stackoverflow.com/questions/6161776/convert-windows-filetime-to-second-in-unix-linux">Convert Windows Filetime to second in Unix/Linux</a> but am stuck at what I should pass to the function <strong>WindowsTickToUnixSeconds</strong>. Judging by the parameter name <em>windowsTicks</em> I tried <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/ms724408%28v=vs.85%29.aspx" rel="noreferrer">GetTickCount</a> but saw shortly after that this returns the ms <strong>since the system started</strong> but I need any reasonable count since the <strong>start of the Windows time</strong> (which seems to was in 1601?).</p>
  
  <p>I saw that windows has a function for retrieving this time: <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/ms724390%28v=vs.85%29.aspx" rel="noreferrer">GetSystemTime</a>. I cannot pass the resulting struct to the proposed function in <a href="https://stackoverflow.com/questions/6161776/convert-windows-filetime-to-second-in-unix-linux">1</a> as it is not a long long value.</p>
  
  <p>Can't someone please just give a full working example for C or C++ without omitting such mad-driving details?</p>