title: Return the url to its original state after refresh
body: <p>I wrote this form using html and PHP  on my webpage. This form receives a number as input. and adds the desired number to 2. And prints the output.</p>
  
  <p>For example, if we put the number 5 at the input and press the submit button , The page refreshes to this URL : mysite.com/page1/?sen=5&amp;sub=Submit</p>
  
  <p>And the number 7 is printed on the output.</p>
  
  <p>So far so good. But when we refresh the page in this case , The submitted information will not be deleted and the url will remain "mysite.com/page1/?sen=5&amp;sub=Submit" .And the output is not cleared and still remains 7.</p>
  
  <p>In this case, I want the page to return to its original state, (mysite.com/page1) . And the output is cleared.</p>
  
  <p>what's the solution?</p>
  
  <pre><code>&lt;form name="form1" action="" method="GET"&gt;
  &lt;input type="number" name="sen" placeholder="سن"&gt;
  &lt;input type="submit" name="sub" placeholder="ثبت"&gt;
  &lt;/form&gt;
  &lt;?php if ( isset($_GET['sub'])){
      //$sen1=0;
       $sen1 = $_GET['sen'];
      if (empty($sen1)){
           echo "ooopppss";
      }
  
  else {
  echo $sen1 + 2; }
  }
  ?&gt;
  
  </code></pre>