1) {
$second = $stack[$n-2];
$stack[$n-2] = $stack[$n-1];
$stack[$n-1] = $second;
}
}
function stack_dup(&$stack) {
$stack[] = $stack[count($stack)-1];
}
$mystack =& stack_initialize();
stack_push($mystack, 73);
stack_push($mystack, 74);
stack_push($mystack, 5);
stack_dup($mystack);
echo 'Stack size is: ', stack_size($mystack), '
';
echo 'Popped off the value: ', stack_pop($mystack), '
';
stack_swap($mystack);
echo 'Current top element is: ', stack_peek($mystack), '
';
stack_destroy($mystack);
?>