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