title: C++ easy way to convert int to string with unknown base
body: <p>Here is code in Java:</p>
  
  <pre><code>int a = 456;
  int b = 5;
  String s = Integer.toString(a, b);
  System.out.println(s);
  </code></pre>
  
  <p>Now I want the same in C++, but all the conversions i find convert to base 10 only. I ofc dont want to implement this by mysleft, why to write something what already exists</p>