Problem with getting count with WordPress

I am trying to display wordpress image using it ID but the code i use is giving an error which is

Warning: count(): Parameter must be an array or an object that implements Countable in /var/www/wordpress/wp-content/themes/monstajamss/template-parts/content-article.php on line 10

This is my code

<div class="image large">
    <?php $thumb_id = get_post_thumbnail_id(get_the_ID()); $alt = get_post_meta($thumb_id, '_wp_attachment_image_alt', true); if(count($alt)) ?>
    <img src="<?php the_post_thumbnail_url('large-size'); ?>" alt="<?php echo $alt; ?>">
</div>

Answer

You are just using get_post_meta incorrectly – it returns an array by default, but you are passing in true as the third parameter which changes it to return a single value only – see the Code Reference for get_post_meta.

Therefore your return value is not array, so you don’t need to try count (which only works with arrays) or anything to evaluate an array of values before using it – it already has a single value so you just need to do the following:

<div class="image large">
    <?php $thumb_id = get_post_thumbnail_id(get_the_ID()); 
          $alt = get_post_meta($thumb_id, '_wp_attachment_image_alt', true); 
     ?>
     <img src="<?php the_post_thumbnail_url('large-size'); ?>" 
         <?php 
          // only include the alt attrib if the alt text is not empty
          // (or you could set a default value, or whatever else you might want to do)
          if ($alt): ?>
             alt="<?php echo $alt; ?>" 
         <?php endif; ?>
     />
</div>