title: verifying if checkbox is checked in php
body: <p>I want to verify if my checkbox is checked in php and if it is, i want to echo "Hello word".
  Here is my html code :</p>
  
  <pre><code>&lt;form class="checkclass"&gt;
  &lt;input type="checkbox" name="checkbox1"&gt; 4K &lt;/input&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>php :</p>
  
  <pre><code> &lt;?php
  if (isset($_POST['checkbox1'])) {
      echo "Hello world!";
  }
  ?&gt;
  </code></pre>
  
  <p>But it doesn't work and i really don't know how to fix this.
  Can someone please help me ?</p>