How to calculate the number of days between two dates in PHP?

Hi everyone! I'm a beginner in PHP and I can't figure out dates. I need to write a script that calculates the number of days between two dates. For example, I want to know how many days have passed since the beginning of the year until today, or how many days are left until New Year.\n\nI tried something like this:\n\n```php\n$date1 = '2023-01-01';\n$date2 = '2023-12-31';\n$days = ($date2 - $date1) / (60 * 60 * 24);\necho $days;\n```\n\nBut it doesn't work — it outputs some nonsense or an error. I understand that strings can't be subtracted like that, but what's the correct way? There are many different tips online: some recommend `strtotime()`, some recommend `DateTime`, and others recommend `date_diff`. I'm completely confused.\n\nPlease tell me the most correct and modern way to find the difference in days between two dates in PHP. It's important that the solution