title: Updating variable value through a function in php
body: <p>I am new in web page development, and it seems that this is a basic question but I can't figure out how to solve.</p>
  
  <p>Through a button I need to change the value of a variable in php, specifically every time a button is pushed the value of a variable must increase.</p>
  
  <p>The code is the following:</p>
  
  <pre><code>     &lt;!DOCTYPE html&gt;
       &lt;html lang="en"&gt;
       &lt;head&gt;
          &lt;meta charset="utf-8"&gt;
          &lt;title&gt;Test&lt;/title&gt;
       &lt;/head&gt;
       &lt;body&gt;
          &lt;script src="http://ajax.googleapis.com/ajax/libs/jquery/1.5/jquery.min.js"&gt;&lt;/script&gt;
          &lt;script&gt;
               function echoVal()
               {
                   alert("&lt;?php val(); ?&gt;");
               }
          &lt;/script&gt;
  
          &lt;?php
               function val() {
                  static $a = 0;
                  $a++;
                  echo $a;
               } 
          ?&gt;
  
          &lt;button onclick="echoVal()"&gt; Increase &lt;/button&gt;
       &lt;/body&gt;
       &lt;/html&gt;
  </code></pre>
  
  <p>The main problem is that the value of the variable $a is always 1, no increasing its value when the button is pushed. I have saved the file with extension .php (I am not sure if that will make any difference, but I just mention it).</p>
  
  <p>Any suggestion to solve this issue?</p>
  
  <p>Thanks in advance for any suggestion.</p>
  
  <p>Edited Code:</p>
  
  <pre><code>     &lt;!DOCTYPE html&gt;
       &lt;html lang="en"&gt;
       &lt;head&gt;
          &lt;meta charset="utf-8"&gt;
          &lt;title&gt;Test&lt;/title&gt;
       &lt;/head&gt;
       &lt;body&gt;
          &lt;script src="http://ajax.googleapis.com/ajax/libs/jquery/1.5/jquery.min.js"&gt;&lt;/script&gt;
          &lt;script&gt;
               function echoVal()
               {
                   alert("&lt;?php val(); ?&gt;");
               }
          &lt;/script&gt;
  
          &lt;?php
               function val() {
                  static $a = 0;
                  $a++;
                  $filename ='infoX.txt';
                  if (is_writable($filename)) {
                      if (!$handle = fopen($filename, 'w')) {
                          echo "Cannot open file";
                      } else {
                          if (fwrite($handle, $a) == FALSE) {
                              echo "Cannot write to file";
                          } else {
                              echo $a;
                          }
                          fclose($handle);
                      }  
                 } else {
                      echo "The file is not writable";
                 }
               } 
          ?&gt;
  
          &lt;button onclick="echoVal()"&gt; Increase &lt;/button&gt;
       &lt;/body&gt;
       &lt;/html&gt;
  </code></pre>