PHP check if variable is smaller than previous item in array

Question

I need a way to check if there are events that overlap each other. So I made an array with the start and end hour of every event. It looks like this:

Array
(
    [0] => Array
        (
            [start] => 0930
            [end] => 1200
        )

    [1] => Array
        (
            [start] => 1000
            [end] => 1230
        )

    [2] => Array
        (
            [start] => 1300
            [end] => 1530
        )

)

This is what I've tried to check if there are events that overlap:

if ( $orders->have_posts() ):
        while ($orders->have_posts()) : $orders->the_post(); 
          foreach($order as $o){
            $start = $o['start'];
            $end = $o['end'];
            $attractieID = $o['attractie']->ID;

            foreach($order as $key => $attractieID){
                $slots[] = array('start' => $start, 'end' => $end);
                if($start < $end){
                   //overlap
                }else{
                   //no overlap
                }
            }
          }
        endwhile; 
endif;

But this will always give true since I am checking the start and end date of the same item in my array.

I need to way to compare the start value of the current array item and the end value of the previous array item

Anyone knows if this is even possible?

Many thanks in advance!

You can't start the body of if with { and end it with endif. — Barmar
– Barmar, Commented Apr 18, 2016 at 15:02
@FrankLucas - Thing about copying code is, it doesn't produce typos. Give actual code. — I wrestled a bear once.
– I wrestled a bear once., Commented Apr 18, 2016 at 15:05
@Pamblam there's a lot of other stuff in my loop that is unrelevant to the question why should I copy it aswel? — Frank Lucas
– Frank Lucas, Commented Apr 18, 2016 at 15:07
copy + delete doesn't produce typos either.... copy + re-write will not only produce typs but will make it difficult for people to answer if one of you "typos" obscures the issue. don't re-write your code just for SO :) — I wrestled a bear once.
– I wrestled a bear once., Commented Apr 18, 2016 at 15:10

Barmar · Accepted Answer · 2016-04-18 15:32:52Z

1

Start looping at index 1, and compare the start time of the current event with the end of the event with index-1.

$count = count($order);
for ($i = 1; $i < $count; $i++) {
    if ($order[$i]['start'] < $order[$i-1]['end']) {
        // overlap
    } else {   
        // no overlap
    }
}

If you want to do this while also copying from $order to slots, you can use a variable to hold the end time from the previous iteration.

  $prevEnd = null;
  foreach($order as $o){
    $start = $o['start'];
    $end = $o['end'];
    $attractieID = $o['attractie']->ID;

    $slots[] = array('start' => $start, 'end' => $end);
    if($prevEnd !== null && $start < $prevEnd){
       //overlap
    }else{
       //no overlap
    }
    $prevEnd = $end;
  }

DEMO

edited Apr 18, 2016 at 15:32

answered Apr 18, 2016 at 15:07

Barmar

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13 Comments

Barmar Over a year ago

What does that have to do with checking for overlap?

Frank Lucas Over a year ago

Because my start and end values are stored in my slots array

Barmar Over a year ago

Aren't they stored in the $order array?

Frank Lucas Over a year ago

Yes but I need to do a check based on the attractie id see the $attractieID = $o['attractie']->ID; in OP

Frank Lucas Over a year ago

In an order you can have multimple events(attracties) every attractie has a start and end value. And I need to check for every event(attractie) if there are overlapping events(attracties)

|

KubiRoazhon · Accepted Answer · 2016-04-18 15:08:41Z

0

Try this code, with a for loop instead of foreach:

for($i=0;$i<count($order);i++){
  $slots[] = array('start' => $start, 'end' => $end);
   if($order[$i+1]){
     if($order[$i]['start'] < $order[$i+1]['end']{
       //overklap
     }else{
      //no overlap
     }
   }

answered Apr 18, 2016 at 15:08

KubiRoazhon

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Comments

Nadir · Accepted Answer · 2016-04-18 15:09:45Z

0

Just use a normal for loop. And, to be sure everything is right, sort the array before checking it (if you are sure it is gona be sorted, you can skip that part)

$sortedOrders = usort($order, function($a, $b)
{
    $aStart = $a['start'];
    $bStart = $b['start'];

    return ($a < $b) ? -1 : 1;  
});

$count = count($sortedOrders);
for($i = 1; $i < $count; $i++)
{
    if($sortedOrders[$i - 1]['end'] > $sortedOrders[$i]['start'])
    {
        // Handle overlap
    }
}

edited Apr 18, 2016 at 15:09

answered Apr 18, 2016 at 15:06

Nadir

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