php_sandbox/booleans.php

   1 <html>
   2 <head>
   3   <title>Booleans and NULL</title>
   4 </head>
   5 <body>
   6 <?php
   7   $bool1 = true;
   8   $bool2 = false;
   9 ?>
  10 $bool1: <?php echo $bool1; ?><br />
  11 $bool2: <?php echo $bool2; ?><br />
  12 <br />
  13 <?php
  14   $var1 = 3;
  15   $var2 = "cat";
  16   $var4 = NULL;
  17 ?>
  18 $var1 is set <?php echo isset($var1); ?><br />
  19 $var2 is set <?php echo isset($var2); ?><br />
  20 $var3 is set <?php echo isset($var3); ?><br />
  21 <?php unset($var1); ?>
  22 $var1 is set <?php echo isset($var1); ?><br />
  23 $var2 is set <?php echo isset($var2); ?><br />
  24 $var3 is set <?php echo isset($var3); ?><br />
  25 <br />
  26 $var1 empty: <?php echo empty($var1); ?><br />
  27 $var4 empty: <?php echo empty($var4); ?><br />
  28 </body>
  29 </html>