您可以有一个authors totals数组，在每次迭代中，您将增加该author的键：

<?php foreach ( $myposts as $post ) : setup_postdata( $post ); ?>
    <?php $author_count = isset( $authors_totals[ get_the_author_meta(\'ID\') ] ) ? int_val( $authors_totals[ get_the_author_meta(\'ID\') ] ) + 1 : 1; ?>
    Date: <?php the_date(\'d/m/Y\'); ?> 
    Title: <?php the_title(); ?> 
    Author: <?php the_author(); ?>: <?php echo $author_count; ?>    
<?php endforeach; ?>

听起来你可以只保留一个计数器，其中的作者已经在列表中了，就像这样

// Counting
$authors_printed = array();
// The Query
$the_query = new WP_Query( $args );
// The Loop
if ( $the_query->have_posts() ) {
    while ( $the_query->have_posts() ) {
        $the_query->the_post();

        $author = get_the_author();
        if (empty($authors_printed[ $author ])) {
            $authors_printed[ $author ] = 1;
        } else {
            $authors_printed[ $author ]++;
        }
        // now $authors_printed[ $author ] has the correct number
        // more code..
    }
}