What are some common challenges when calculating hours between two time points in PHP, especially when rounding to quarter hours?

When calculating hours between two time points in PHP and rounding to quarter hours, a common challenge is handling time formats and accurately calculating the time differences. One way to solve this is by converting the time points to timestamps, calculating the difference in seconds, converting it back to hours, and then rounding it to the nearest quarter hour.

// Convert time points to timestamps
$start_time = strtotime('09:30');
$end_time = strtotime('14:45');

// Calculate time difference in seconds
$time_diff = $end_time - $start_time;

// Convert time difference to hours
$hours = $time_diff / 3600;

// Round hours to the nearest quarter hour
$rounded_hours = round($hours * 4) / 4;

echo "Hours between the two time points: " . $rounded_hours;