Display Post Word Count Shortcode

<?php
/**
 * Usage: [word_count]
 * Optional: [word_count post_id="42"]
 * Returns the plain integer word count of the post body.
 */
add_shortcode( 'word_count', 'scseed_word_count_shortcode' );
function scseed_word_count_shortcode( $atts ) {
    $atts = shortcode_atts(
        array( 'post_id' => 0 ),
        $atts,
        'word_count'
    );
    $post_id = $atts['post_id'] ? absint( $atts['post_id'] ) : get_the_ID();
    if ( ! $post_id ) {
        return '0';
    }
    $content = get_post_field( 'post_content', $post_id );
    $content = strip_shortcodes( $content );
    $content = wp_strip_all_tags( $content );
    $words   = preg_split( '/\s+/', trim( $content ), -1, PREG_SPLIT_NO_EMPTY );
    return (string) count( (array) $words );
}