For working with people data, there are two ways to store age, that is as an integer or as a date of birth. The latter is generally preferred because it does not require anyone to manually update that information.
Therefore, this repository contains a PHP class with properties where is defined the get_age() function. Then, is converted the person's date of birth in the format YYYY-MM-DD to an age in years.
PHP has a very helpful build-in function the DateTime class that help us convert a date of virtually any format into something we can use for conversions. So, in this case with function get_age() it's converted a date of birth to a new DateTime class and inside it is sent the date of birth that is a property of the object. Then, with function Date it's get today's date.
Finally, with function diff is substracted date of birth from today's date. With the PHP year property, only the age number of the specified person from the Person class is returned.
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