Source

File: wp-admin/includes/template.php

function wp_star_rating( $args = array() ) {
	$defaults    = array(
		'rating' => 0,
		'type'   => 'rating',
		'number' => 0,
		'echo'   => true,
	);
	$parsed_args = wp_parse_args( $args, $defaults );

	// Non-English decimal places when the $rating is coming from a string.
	$rating = (float) str_replace( ',', '.', $parsed_args['rating'] );

	// Convert percentage to star rating, 0..5 in .5 increments.
	if ( 'percent' === $parsed_args['type'] ) {
		$rating = round( $rating / 10, 0 ) / 2;
	}

	// Calculate the number of each type of star needed.
	$full_stars  = floor( $rating );
	$half_stars  = ceil( $rating - $full_stars );
	$empty_stars = 5 - $full_stars - $half_stars;

	if ( $parsed_args['number'] ) {
		/* translators: 1: The rating, 2: The number of ratings. */
		$format = _n( '%1$s rating based on %2$s rating', '%1$s rating based on %2$s ratings', $parsed_args['number'] );
		$title  = sprintf( $format, number_format_i18n( $rating, 1 ), number_format_i18n( $parsed_args['number'] ) );
	} else {
		/* translators: %s: The rating. */
		$title = sprintf( __( '%s rating' ), number_format_i18n( $rating, 1 ) );
	}

	$output  = '<div class="star-rating">';
	$output .= '<span class="screen-reader-text">' . $title . '</span>';
	$output .= str_repeat( '<div class="star star-full" aria-hidden="true"></div>', $full_stars );
	$output .= str_repeat( '<div class="star star-half" aria-hidden="true"></div>', $half_stars );
	$output .= str_repeat( '<div class="star star-empty" aria-hidden="true"></div>', $empty_stars );
	$output .= '</div>';

	if ( $parsed_args['echo'] ) {
		echo $output;
	}

	return $output;
}