//NULL.php

var1 contains Hello
var2 contains NULL
var3 contains 10
var4 contains 20
<br />
<b>Warning</b>:  Undefined variable $var1 in <b>/home/course/u30/public_html/examples_php_general/core/NULL.php</b> on line <b>27</b><br />
var1 contains NULL
<br />
<b>Warning</b>:  Undefined variable $var2 in <b>/home/course/u30/public_html/examples_php_general/core/NULL.php</b> on line <b>30</b><br />
var2 contains NULL
<br />
<b>Warning</b>:  Undefined variable $var3 in <b>/home/course/u30/public_html/examples_php_general/core/NULL.php</b> on line <b>33</b><br />
var3 contains NULL
<br />
<b>Warning</b>:  Undefined variable $var4 in <b>/home/course/u30/public_html/examples_php_general/core/NULL.php</b> on line <b>36</b><br />
var4 contains NULL