get_the_modified_date

 * Date string output can be filtered with 'get_the_date'.
 *
 * @since 0.71
 *
 * @global string $currentday  The day of the current post in the loop.
 * @global string $previousday The day of the previous post in the loop.
 *
 * @param string $format Optional. PHP date format defaults to the date_format option if not specified.
 * @param string $before Optional. Output before the date.
 * @param string $after  Optional. Output after the date.
 * @param bool   $echo   Optional. Whether to echo the date or return it. Default true.
 * @return string|void String if retrieving.
 */
function the_date( $format = '', $before = '', $after = '', $echo = true ) {
	global $currentday, $previousday;

	$the_date = '';

	if ( is_new_day() ) {
		$the_date    = $before . get_the_date( $format ) . $after;
		$previousday = $currentday;
	}

	/**
	 * Filters the date a post was published for display.