title: Why do the fast IO methods like this, work in c++?
body: <p>Fast I/O methods like the following are used in C++ for competitive coding, which don't push output to STDIO, and rather keep it in buffer, making I/O much faster than normal cout. Why does this output method work faster than putchar_unlocked() of C? 
  (I think that cout uses putchar in background.)</p>
  
  <pre><code>#include &lt;bits/stdc++.h&gt;
  using namespace std;
  
  int main()
  {
      ios_base::sync_with_stdio(false);
      cin.tie(NULL);
      return 0;
  }
  </code></pre>