//How to call the function "yearOfBirth" person.yearOfBirth //or person.yearOfBirth()

Question

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Answer 1

If it is a function, you use parenthesis to call it.
If you are assigning it as callback, then you don't use parenthesis.

Answer 2

Considering that person is a reference to an object of a class. You can call it by person.yearOfBirth();
Also you can use the code playground to run and see it for yourself.