multiple nested IFs possible in view?

[eluser]cleansugar[/eluser]

Code:

<?php if (a == 0) :?>
     <?php if (a == 0) :?>
     <?php else:?>
          <?php echo(a); ?>
     <?php endif;?>
<?php else:?>
      <?php echo(b); ?>
<?php endif;?>

I want to make IF in IF in view.
But when I run the view, both echo a and echo b executed.
Is it impossible multiple ifs?