wordrpess the_excerpt()函数截取字符无效

/**
 * Display the post excerpt.
 *
 * @since 0.71
 * @uses apply_filters() Calls 'the_excerpt' hook on post excerpt.
 */
function the_excerpt() {
        echo apply_filters('the_excerpt', get_the_excerpt());
}

/**
 * Retrieve the post excerpt.
 *
 * @since 0.71
 *
 * @param mixed $deprecated Not used.
 * @return string
 */
function get_the_excerpt( $deprecated = '' ) {
        if ( !empty( $deprecated ) )
                _deprecated_argument( __FUNCTION__, '2.3' );

        $post = get_post();

        if ( post_password_required() ) {
                return __( 'There is no excerpt because this is a protected post.' );
        }

        return apply_filters( 'get_the_excerpt', $post->post_excerpt );
}