How to Calculate Seconds Until the End of the Day in PHP

Since there is no such built-in function in PHP, I had to write my own implementation:

function get_seconds_to_midnight()
{
	$left_day_hh = 23 - intval(date('H'));
	$left_day_mm = 59 - intval(date('i'));
	$left_day_ss = 60 - intval(date('s'));
	
	return 3600 * $left_day_hh + 60 * $left_day_mm + $left_day_ss;
}

For testing, we use the following code:

echo 'SECONDS: '.get_seconds_to_midnight().'<hr>';
echo 'NOW: '.date('d.m.Y H:i:s').'<hr>';
echo 'MIDNIGHT: '.date('d.m.Y H:i:s', time() + get_seconds_to_midnight()).'<hr>';

In short, we subtract the current time from the end-of-day time and get the difference in seconds by converting hours and minutes and adding seconds.