tryphp_func_var_isset.php:
<!DOCTYPE html> <html> <body> <?php $a = 0; // True because $a is set if (isset($a)) { echo "Variable 'a' is set.<br>"; } $b = null; // False because $b is NULL if (isset($b)) { echo "Variable 'b' is set."; } ?> </body> </html>
Variable 'a' is set.