How to organize and output events by date in a loop

how-to-organize-and-output-events-by-date-in-a-php-loop.php

<?php 

// Example using a while loop (inside WordPress in this case)

$already_echoed = array()
while ( have_posts() ) : the_post(); 
if (!in_array($date, $already_echoed)) { //check if current date is in the already_echoed array
    echo $date;   
}
$already_echoed[] = $date; //store all dates in an array to check against.

// Example using a foreach loop

$already_echoed = array();
foreach ($events as $event) {
    if (!in_array($event->date, $already_echoed)) {
        echo $event->date . "<br />";   
    }
    $already_echoed[] = $event->date;
}