title: Index specification in printf format specifier
body: <p>In the following program, <code>printf()</code> function print according to argument index specification.</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  
  int main()
  {
          printf("%3$d  %4$f  %2$d  %1$d\n", 1,  2,  3,  4.5);
  }
  </code></pre>
  
  <p><strong>Output:</strong></p>
  
  <pre><code>3  4.500000  2  1
  </code></pre>
  
  <p>So, I have question, <strong>Is it valid for any compiler or support only GCC compiler?</strong></p>