How to get author's name by author's id

I want to show recent posts like this.

<ul id="recent-posts">
  <?php foreach( wp_get_recent_posts() as $recent ){ ?>
    <li>
      <a href="<?php echo get_permalink($recent['ID']); ?>">
    <?php echo $recent["post_title"]; ?> by
    <?php echo $recent["post_author"]; ?>
      </a>
    </li>
  <?php } ?>
</ul>

But $recent["post_author"] returns only id of author. And this is outside The Loop, so I can’t use the_author() function.

How can I get author’s name from ID?
Or maybe there is a better way to do it?

Solutions Collecting From Web of "How to get author's name by author's id"

Try get_user_by():

get_user_by( $field, $value );

In your case, you’d pass ID, and the user ID:

// Get user object
$recent_author = get_user_by( 'ID', $recent["post_author"] );
// Get user display name
$author_display_name = $recent_author->display_name;
echo get_the_author_meta('display_name', $recent["post_author"]);
// code from deprecated.php function @get_author_name

More examples of get_the_author_meta($meta_key, $author_id) you can find at Codex.

The wp_posts table, which is the one you are querying with wp_get_recent_posts() does not include an author name column. It only carries the author ID (as you have already found out).

So, what you have to do is use another WordPress function called get_user_by(). This will allow you to take the author ID and find the corresponding author name.

Something like this should work (untested):

<ul id="recent-posts">
<?php foreach( wp_get_recent_posts() as $recent ){

    $user_id = get_user_by('id', $recent["post_author"]);  // Get user name by user id
        ?>
        <li>
        <a href="<?php echo get_permalink($recent['ID']); ?>">
        <?php echo $recent["post_title"]; ?> by
        <?php echo $user_id->display_name; ?>
        </a>
        </li>
    <?php 
    } ?>
</ul>

In your case this could work:

<?php $user_info = get_userdata($recent["post_author"]);
echo $user_info->user_login; ?>