计算循环按字生成的帖子

在我的类别页面上，我将每个帖子显示为li。我想为每个 li 分配一个从 1 开始并逐步计数的 ID（即，如果一个类别有 10 个帖子，则输出是一个 ul，每个 li 都有一个 ID 从 1 到 10 的数字。我将如何实现这一点？

分类.php：

<?php
/**
 * The template for displaying category pages.
 **/
get_header(); 
$counter = 0;?>
    <div id="primary" class="content-area">
        <main id="main" class="site-main" role="main">
        <?php
                if ( have_posts() ) : ?>
                    <header class="page-header">
                <?php
                    the_archive_title( '<h1 class="page-title">', '</h1>' );
                    the_archive_description( '<div class="taxonomy-description">', '</div>' );
                ?>
                    </header><!-- .page-header -->
                        <div class="slider-cont">
                        <div class="slider-nav">
                            <i class="fa fa-chevron-left"></i>
                        </div>
                        <div id="slider">
                        <ul class="slides">
            <?php
            /* Start the Loop */
            while ( have_posts() ) : the_post();
                        $counter++;
                /*
                 * Include the Post-Format-specific template for the content.
                 * If you want to override this in a child theme, then include a file
                 * called content-___.php (where ___ is the Post Format name) and that will be used instead.
                 */
                get_template_part( 'template-parts/content-category', get_post_format() );
            endwhile;?>
                        </ul>
                        </div>
        <div class="slider-nav next">
            <i class="fa fa-chevron-right"></i>
        </div>
            <?php the_posts_navigation();
        else :
            get_template_part( 'template-parts/content', 'none' );
        endif; ?>
                    </div><!-- .slider-cont -->
        </main><!-- #main -->
    </div><!-- #primary -->

和内容类别.php：

<?php
get_footer();
<li class="slide" id="post<?php $counter; ?>">
    <article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
            <header class="entry-header">
                    <h2><?php echo the_title();
                    if ( 'post' === get_post_type() ) : ?></h2>
                    <?php
                    endif; ?>
            </header><!-- .entry-header -->
            <div class="entry-content">
                    <?php echo the_excerpt();?>
                     <a href="<?php echo the_permalink();?>">Read More.</a>
            </div><!-- .entry-content -->
    </article><!-- #post-## -->
</li>

提前感谢！