How to check if two times overlap in PHP? - php

Question

So I'm trying to figure out how to check if two times overlap using PHP and a MySQL database.
This is the function I'm using to check if they are overlapping:
function testRange($start_time1,$end_time1,$start_time2,$end_time2) {
return ($end_time1 < $start_time2) ? false : ($start_time1 > $start_time2) && ($start_time1 > $end_time2) ? false : true;
}
AFAIK that should work fine so I go to check if the times are overlapping and add any that do overlap to an array:
$clashes = [];
$idTracker = [];
foreach ($userBands as $show) {
foreach ($userBands as $show1) {
if(!($show->id == $show1->id)) {
if(strcmp($show->date, $show1->date) == 0 && testRange(strtotime($show->time), strtotime($show->time) + ($show->length*60), strtotime($show1->time), strtotime($show1->time) + ($show1->length*60))) {
array_push($clashes, [
"s1_id" => $show->id,
"s2_id" => $show1->id
]);
}
}
}
}
foreach ($clashes as $clash) {
foreach ($clashes as $clash1) {
//If Clash1->ID1 == Clash2->ID1 then
}
print_r($clash);
echo "<br>";
}
However when I print out the entries of the $clashes array I get this as my output:
which is just wrong completely as this is the contents of the database:
27 and 26 should not be clashing with 25, but they are being tracked into the $clashes array. Why is this happening?
Database Info:
Date is of the Date SQL type, Time is of the Time SQL type and Length is a double(8,2) SQL type
$userBands Info:
The $userBands variable is a Laravel collection of the Show model

Answer 1

First:
You can change the SQL query to get end-time like so:
SELECT *,
ADDTIME(
CONCAT(time,'.0'),
CONCAT(CONCAT(CONCAT( length DIV 60, ':' ), length MOD 60) ,':0.0')
) AS EndTime
FROM `table`;
So now you have a column named EndTime,
So this code can work:
if(strcmp($show->date, $show1->date) == 0 &&
newTestRange(
strtotime($show->time),
strtotime($show->EndTime),
strtotime($show1->time),
strtotime($show1->EndTime)
) ) {
I have no idea why this works:
function newTestRange($start_time1,$end_time1,$start_time2,$end_time2) {
// 12:30:00 13:20:00 12:45:00 13:45:00
// return ($end_time1 < $start_time2) ? false : ($start_time1 > $start_time2) && ($start_time1 > $end_time2) ? false : true;
$ret = false; // its all okay.
if ($start_time1 < $start_time2 ){
if ($end_time1 > $start_time2 ){
$ret = true;echo "\n case1-$start_time1-colide-$start_time2 \n";
}
} else if ($end_time2 > $start_time1){
$ret = true; echo "\n case2-$start_time1-colide-$start_time2 \n";
}
return $ret;
}
but you must consider 4 different scenarios:
So if one event contains another event, you will find it.
Best!

Answer 2

Fixed it by changing the algorithm for comparing the times.
New version:
function testRange($s1, $e1, $s2, $e2) {
return $s1 <= $e2 && $s2 <= $e1;
}
Don't know why this works over the previous one however.