Hi. In this video, we're going to see how we can control access to the data hosted in our objects. You'll notice, or you'll remember, from the previous video, we could set the balance of an account object to any value we liked, overwriting what was already in there and maybe setting it to ridiculous values. Is there any way of controlling this and restricting that behaviour? And the answer is, yes.

In the existing program, we had a 'Balance' property, declared with a 'get' and 'set' clause. I have a new version of the app defined in project two, and my 'BankAccount' class has a balance property, but you'll notice the 'set' clause is declared as 'private'. When something's declared as private, it's private to the class that it's defined in, and so the code inside the class can refer to the balance property and can set it to whatever values it deems appropriate. So I'm setting it in the constructor, I'm setting it in 'WithdrawMoney', down here, and I'm setting it in 'DepositMoney' on line 40. So that's fine, but the client code in this project, when I try and adjust the balance directly, is denied access to that.

If I hover the mouse over the error message, it tells me that, 'the property or index of BankAccount.Balance cannot be used in this context because the set accessor is inaccessible.' It's private, so I can't directly set it, I can only get to it indirectly via the mechanisms of passing it to a constructor, or calling the 'DepositMoney' or 'WithdrawMoney' methods.

So, in this video we've seen how we can restrict access to our data by making the getter clauses private.

Practical example of controlling access to data

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