title: how "%1$s" and "%2$s" are converted into String in Wordpress
body: <p>Usually , when you use sprintf, you will write down %s and matching actual value like below(" %s " = "p" , "%s" = " #999 "  etc)</p>
  
  <pre><code>&lt;?php
    $output = sprintf(
      '&lt;%s style="color:%s"&gt;%s&lt;/%s&gt;', 
      'p', 
      '#999',
      'Text', 
      'p' 
    ); 
    echo $output;
  ?&gt;
  </code></pre>
  
  <p>But in register_sidebar() method of wordpress, I know %1$1 and %2$s is coverted into "widgetName-Number"(id) and "widget widget_widgetName"(class) by sprintf. </p>
  
  <p>But I dont know how they converted "%1$1" and "%2$s" into these values??(Because these values are not mentioned in register_sidebar() method) </p>
  
  <pre><code>register_sidebar(
       array(
        'name' =&gt; 'sidebar', 
        'id' =&gt; 'sidebar', 
        'before_widget' =&gt; '&lt;div id="%1$s" class="widget %2$s"&gt;',
        'after_widget' =&gt; '&lt;/div&gt;',
        'before_title' =&gt; '&lt;div class="widget-title"&gt;',
        'after_title' =&gt; '&lt;/div&gt;',
       )
   );
  </code></pre>