Wordpress text filed input only inter value?

Question

All

Now i am using WordPress, here right now i have a problem How can i valid my text filed input only inter value. Here is my code

<p>
  <label for="<?php echo $this->get_field_id('num_post'); ?>">
    <?php _e( 'Number of posts to show:' ); ?>
    <input id="<?php echo $this->get_field_id( 'num_post' ); ?>" name="<?php echo $this->get_field_name( 'num_post' ); ?>" type="text" value="<?php echo   $instance['num_post']; ?>" size="3" />
  </label>
</p>

Answer 1

<?php print (int) $instance['num_post']; ?>

or possibly:

<?php print absint( $instance['num_post'] ); ?>

Use the second one to avoid negative values.