Sort by time PHP - php

Question

i have this function sort_by_time, the purpose of this function is to swap the time1 if the time2 is greater than time1 but my problem is im having an error of Undefined offset: 0. Sometimes the error is Undefined offset: 1. or Undefined offset: 2. Can someone help me to prevent this error in my code? I'm thinking this in these last 3 days but i can't think of any solution on this.
in this line the error occur.
if (Payroll2::convert_time_in_minutes($_time[$j]->time_in) > Payroll2::convert_time_in_minutes($_time[$j+1]->time_in))
This error occurs because the $_time[0] is not set.
Sample time. This is dynamic not only limited to 3 sometimes it's 4, sometimes it's 5 or 1.
1 => {#6356}
2 => {#6352}
3 => {#6257}
Here's my full function code
public static function sort_by_time($_time)
{
$count = 0;
$n = count($_time);
for ($i = 0; $i < $n-1; $i++)
{
for ($j = 0; $j < $n-$i-1; $j++)
{
if (Payroll2::convert_time_in_minutes($_time[$j]->time_in) > Payroll2::convert_time_in_minutes($_time[$j+1]->time_in))
{
// swap temp and arr[i]
$temp = $_time[$j];
$_time[$j] = $_time[$j+1];
$_time[$j+1] = $temp;
}
}
}
return $_time;
}

Answer 1

Try this:
public static function sort_by_time($_time)
{
usort($_time,function($ad,$bd)
{
$ad = Payroll2::convert_time_in_minutes($ad->time_in);
$bd = Payroll2::convert_time_in_minutes($bd->time_in);
if ($ad == $bd) {
return 0;
}
return $ad < $bd ? -1 : 1;
});
return $_time;
}
if it doesn't work the problem can be in function Payroll2::convert_time_in_minutes