title: php default arguments
body: <p>In PHP, if I have a function written like this</p>
  
  <pre><code>function example($argument1, $argument2="", $argument3="")
  </code></pre>
  
  <p>And I can  call this function in other place like this</p>
  
  <pre><code>example($argument1)
  </code></pre>
  
  <p>But if I want to give some value to the thrid argument,
  Should I do this</p>
  
  <pre><code>example($argument1, "", "test");
  </code></pre>
  
  <p>Or</p>
  
  <pre><code> example($argument1, NULL, "test");
  </code></pre>
  
  <p>I think both will work but what is the better way? Because in future if the value for the $argument2 is changed in the main function and if I have "", then will there be any problem? Or NULL is the best option?</p>
  
  <p>Thanks</p>