Displays or retrieves the date the current post was written (once per date)

Will only output the date if the current post’s date is different from the
previous one output.

i.e. Only one date listing will show per day worth of posts shown in the loop, even if the
function is called several times for each post.

HTML output can be filtered with ‘the_date’.
Date string output can be filtered with ‘get_the_date’.

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.
	 *
	 * @since 0.71
	 *
	 * @param string $the_date The formatted date string.
	 * @param string $format   PHP date format.
	 * @param string $before   HTML output before the date.
	 * @param string $after    HTML output after the date.
	 */
	$the_date = apply_filters( 'the_date', $the_date, $format, $before, $after );

	if ( $echo ) {
		echo $the_date;
	} else {
		return $the_date;
	}
}