Code for displaying WordPress post list from a category

Code for displaying WordPress post list from a category in custom page

<?php query_posts(‘posts_per_page=3&category_name=categoryslug’); ?>

<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

<div style="width:100%; float:left; margin-bottom:10px;"> <a href="<?php echo the_permalink(); ?>"><?php the_post_thumbnail(‘medium’, array(‘class’ => ‘alignleft’)); ?></a>

<h5> <a href="<?php echo the_permalink(); ?>">

<?php the_title(); ?>

</a> </h5>

<p>

<?php echo substr(get_the_excerpt(),0,40).(get_the_excerpt() ? "…" : "" ); ?>

</p>

</div>

<?php endwhile; else: ?>

<?php endif; ?>

<?php wp_reset_query(); ?>