如何正确比较php中的日期与相同的格式

Trying to do a simple date comparison. Both dates are in the format of "Y F jS, g:i a". e.g. 2018 September 3rd, 9:30 am.

$today = date('Y F jS, g:i a');
$expire = file_get_contents(dirname(__FILE__).'/maintenance/end_time.php');

if($today>$expire){
  unlink(dirname(__FILE__).'/maintenance/end_time.php');
}

The code I have doesn't work correctly. I also tried strototime() but that was also unsuccessful.

Try this.

$today_dt = new DateTime($today);
$expire_dt = new DateTime($expire);

if ($today_dt > $expire_dt) 
 { /* Do something */ }

Update: It might possible that the date string is not supported by DateTime parser so you can initialize your dates like this.

$today_dt = DateTime::createFromFormat('Y F jS, g:i a', $today);
$expire_dt = DateTime::createFromFormat('Y F jS, g:i a', $expire);

Use strtotime

$today = time();
$expire = strtotime(file_get_contents(dirname(__FILE__).'/maintenance/end_time.php'));

if($today>$expire){
  //code
}

OR

$today = date('Y F jS, g:i a');
$expire = file_get_contents(dirname(__FILE__).'/maintenance/end_time.php');

if(strtotime($today) > strtotime($expire)){
  unlink(dirname(__FILE__).'/maintenance/end_time.php');
}