PHP - If variable is not empty, echo some html code

I would like to display some html code if a variable is not empty, else I would like to display nothing.

I've tried this code but doesn't work:

<?php 
    $web = the_field('website');
    if (isset($web)) {
?>
       <span class="field-label">Website: </span><a href="http://<?php the_field('website'); ?>" target="_blank"><?php the_field('website'); ?></a> 
<?php
    } else { 
        echo "Niente";
    }
?>

Solution 1:

if (!empty($web)) {
?>
    <span class="field-label">Website:  </span><a href="http://<?php the_field('website'); ?>" target="_blank"><?php the_field('website'); ?></a> 
<?php
} else { echo "Niente";}

http://us.php.net/manual/en/function.empty.php

Solution 2:

isset will return true even if the variable is "". isset returns false only if a variable is null. What you should be doing:

if (!empty($web)) {
    // foo
}

This will check that he variable is not empty.

Hope this helps