Split a string to tow Datetime objects

If you are sure your that your input will always have the same structure, you could use something like this:

list($start, $end) = explode('-', str_replace(':','h','09:00-18:00'));

Your variable $start will contain '09h00' and $end will contain '18h00'

You need to use DateTime::createFromFormat

$line = '09:00-18:00';

$split = explode('-', $line);

$start = DateTime::createFromFormat ( 'H:m', $split[0]);
$end = DateTime::createFromFormat ( 'H:m', $split[1]);

print_r($start);
echo '>>>';
print_r($end);

You can check the online Demo

date_create and new DateTime recognize hh:mm and hh:mm:ss even without format specifications. The date is set to the current date.

$line = '09:00-18:00';

$parts = explode('-', $line);

$start = date_create($parts[0]);
$end   = date_create($parts[1]);

var_dump($start, $end);

Output:

object(DateTime)#1 (3) {
  ["date"]=>
  string(26) "2019-11-07 09:00:00.000000"
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(13) "Europe/Berlin"
}
object(DateTime)#2 (3) {
  ["date"]=>
  string(26) "2019-11-07 18:00:00.000000"
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(13) "Europe/Berlin"
}

A very short variant that returns an array with 2 datetime objects:

$line = '09:00-18:00';

$array = array_map('date_create',explode('-', $line));

Update:

A strict format check can be realized with regular expressions.

if(preg_match('/^([01][0-9]|2[0-3]):[0-5][0-9]-([01][0-9]|2[0-3]):[0-5][0-9]$/',$line)){
  //processing

}
else {
  //format error
}