title: NULL arg allowed to sscanf?
body: <p>Is a <code>NULL</code> pointer allowed as the string to store result in in a call to <code>sscanf</code>?</p>
  <p>I don't find anything about it in any documentation but it seems to be working fine. Same thing with <code>scanf</code>.</p>
  <p>Example:</p>
  <pre><code>int main(int arc, char* argv[])
  {
    char* s = NULL;
    sscanf(&quot;Privjet mir!&quot;, &quot;%s&quot;, s);
    printf(&quot;s: %s\n&quot;, s);
    return 0;
  }
  </code></pre>
  <p>Output: <code>s: (null)</code></p>