WordPressの投稿ループで子カテゴリーだけを表示する方法：子カテゴリーを表示する

if ( has_category() || has_tag() ) {

				echo '<div class="post-taxonomies">';

				$categories_list = get_the_category_list( wp_get_list_item_separator() );
				if ( $categories_list ) {
					printf(
						/* translators: %s: List of categories. */
						'<span class="cat-links">' . esc_html__( 'Categorized as %s', 'twentytwentyone' ) . ' </span>',
						$categories_list // phpcs:ignore WordPress.Security.EscapeOutput
					);
				}

				$tags_list = get_the_tag_list( '', wp_get_list_item_separator() );
				if ( $tags_list && ! is_wp_error( $tags_list ) ) {
					printf(
						/* translators: %s: List of tags. */
						'<span class="tags-links">' . esc_html__( 'Tagged %s', 'twentytwentyone' ) . '</span>',
						$tags_list // phpcs:ignore WordPress.Security.EscapeOutput
					);
				}
				echo '</div>';
			}
		} else {

if ( has_category() || has_tag() ) {

    echo '<div class="post-taxonomies">';

    // Get the list of categories
    $categories = get_the_category();
    $child_cat_IDs = array(); // Array to store child category IDs
    $parent_cat_IDs = array(); // Array to store parent category IDs
 
    foreach ( $categories as $category ) {
        if ( $category->parent > 0 ) {
            $child_cat_IDs[] = $category->term_id; // Store the child category ID
        } else {
            $parent_cat_IDs[] = $category->term_id; // Store the parent category ID
        }
    }

    // Output child categories if there are any
    if ( !empty($child_cat_IDs) ) {
        $output = '<span class="cat-links">' . esc_html__( 'Categorized as ', 'twentytwentyone' ) . ' ';
        foreach ( $child_cat_IDs as $cat_id ) {
            $cat_link = get_category_link($cat_id);
            $cat_name = get_cat_name($cat_id);
            $output .= '<a href="' . esc_url($cat_link) . '">' . esc_html($cat_name) . '</a> ';
        }
        $output .= '</span>'; // Close the span tag after the loop
        echo $output; // Output the child category links

    // Output parent categories if there are no child categories
    } elseif ( !empty($parent_cat_IDs) ) {
        $output = '<span class="cat-links">' . esc_html__( 'Categorized as ', 'twentytwentyone' ) . ' ';
        foreach ( $parent_cat_IDs as $cat_id ) {
            $cat_link = get_category_link($cat_id);
            $cat_name = get_cat_name($cat_id);
            $output .= '<a href="' . esc_url($cat_link) . '">' . esc_html($cat_name) . '</a> ';
        }
        $output .= '</span>'; // Close the span tag after the loop
        echo $output; // Output the parent category links
    }

    // Handle tags
    $tags_list = get_the_tag_list('', wp_get_list_item_separator());
    if ( $tags_list && ! is_wp_error( $tags_list ) ) {
        printf(
            /* translators: %s: List of tags. */
            '<span class="tags-links">' . esc_html__( 'Tagged %s', 'twentytwentyone' ) . '</span>',
            $tags_list // phpcs:ignore WordPress.Security.EscapeOutput
        );
    }

    echo '</div>'; // Close post-taxonomies div
}
} else {