what is the meaning of data hiding

Question

One of the most important aspects of OOP is data hiding. Can somebody explain using a simple piece of code what data hiding is exactly and why we need it?

Answer 1

I'm guessing by data hiding you mean something like encapsulation or having a variable within an object and only exposing it by get and modify methods, usually when you want to enforce some logic to do with setting a value?

public class Customer
{
    private decimal _accountBalance;

    public decimal GetBalance()
    {
        return _accountBalance;
    }

    public void AddCharge(decimal charge)
    {
        _accountBalance += charge;
        if (_accountBalance < 0)
        {
            throw new ArgumentException(
                "The charge cannot put the customer in credit");
        }
    }    
}

I.e. in this example, I'm allowing the consuming class to get the balance of the Customer, but I'm not allowing them to set it directly. However I've exposed a method that allows me to modify the _accountBalance within the class instance by adding to it via a charge in an AddCharge method.

Here's an article you may find useful.