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Welcome back. We're in the last part of the solution to the challenge for section 16.

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The only thing we've got left to do is clean up those account util files,

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so that we don't have all this duplicated code.

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So I'm in the challenge solution project.

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And this challenge solution project right now is exactly like we left off part 2.

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So the first thing we want to do is we want to look at these helper functions,

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and we really want to get rid of all of them except what we absolutely need.

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And what we absolutely do need is, remember, we're going to come at these things now with

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base class pointers,

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so that way we can just use dynamic binding and only have one version of them.

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So that's what we're going to do. We're going to keep display deposit and withdraw.

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But instead of having a vector of account objects, we're going to have a vector of

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pointers to account objects.

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That's my base class pointer. That's what really gives me the power of dynamic polymorphism.

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So that's what I need to do.

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All of these down here I can get rid of.

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I don't need specialized versions of these things because the whole point of

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dynamic polymorphism is to let the runtime system figure out

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which one to use.

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So this is what we want to reduce it to.

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I'm going to modify that to say pointer classes because that's really what we are

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and also these include files. Notice that the only thing we really care about is account,

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so we don't need all these include files, we can get rid of them. We only need the account.

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Okay. So that's where we're at now.

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Now the implementation for all of those functions, let's go to that file.

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So in the account util cpp file,

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we only want to keep the first three, and we're going to modify them slightly.

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The rest of them we can

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just get rid of because those are the specialized versions for savings, checking account and trust account.

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And those were assuming static binding. So we're not doing static binding anymore, so we don't need them at all.

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So let's get rid of them.

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And this is what I've got now. I've got three functions:display,

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deposit and withdraw.

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Now we do need to modify them slightly because our prototypes now expect

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pointers right here.

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So that's a pointer,

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and I'm just going to say account object pointers because that's really what we are.

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So let's take a look at this for a second and understand what's going on here.

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In this case, I've got for const, auto.

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There's my account, right. Now this is -- this needs to change a little bit

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because I don't really want a reference. I already have a pointer,

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so I don't need that at all. I just need to get rid of that.

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And then now since auto will be a pointer, I just need to de-reference the pointer here.

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That's an object, and that will call the overloaded operator

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that we just created,the insertion operator.

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So that's just a really precise change, but that's all we need to do here.

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The same with deposit. In deposit, we've got account pointers again,

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so we'll change that because the vector is a little different.

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And we don't need the reference here because we've got a pointer.

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But what do we do now.

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Well, we've got to call the deposit method right, but we have a pointer, so we just need to change the operator

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to the arrow operator.

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That's it.

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And then here with withdraw, last step,

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again,we've got pointers to accounts in the vector.

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So what do we do here, same idea. Get rid of the reference because we've got pointers there,

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and we call account withdraw from the pointer.

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We also need to make a couple of changes right here.

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We need to dereference that pointer to get the account here as well,

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that will also call the overloaded insertion operator.

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We need to dereference the pointer here to get the object and here as well.

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And that should do it. You can see how much

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code we got rid of. We got rid of a ton of code,

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and we've simplified our project, we've simplified our thinking.

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We can come at these now with base class pointers

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and let the runtime system figure out which method to bind.

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All right. So now let's go to our main and take a look.

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Here's our main. There's a whole bunch of stuff in here. Let's give it a run and see what happens.

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There we go. There's our run. You can see here I'm creating a checking account.

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Again, this is not a pointer, so this is just creating a plain object on the stack.

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Frank with 5000, there it is.

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Now I'm creating a trust account, and I'm creating that account dynamically

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through a base class pointer. And there's James.

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No balance, no interest and no withdrawals.

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And notice how we were able to print that

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on the stream just because we're using our overloaded operators and it's printing it correctly.

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Now we're creating Larry, Moe, and Curly as three pointers to accounts.

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And again,

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we're create -- we're instantiating a checking account, a savings account and a trust account.

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And then we're adding those three pointers to this vector accounts.

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Now we're calling display accounts, that's that function that we just

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updated in the account util.

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And it's going to display the three accounts, and I expect dynamic binding.

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That's exactly what happens. You can see right here:

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checking, savings and trust. That's, pretty cool.

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Then we deposit a 1000 dollars into each one of those accounts. You can see right here

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I'm depositing a 1000 to checking, to savings and to trust.

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Finally, we're withdrawing 2000,

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that's this code right here. You can see the last one fails because there's not enough balance.

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And then finally, we display the accounts one last time, and we see the balances.

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We clean up our pointers, and we're done. Now we're done.

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The challenge is over. I hope you had a fun time doing it.

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If you had trouble with it, don't worry.

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This was not an easy challenge. This was a very, very challenging exercise.

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Go back and understand what I did compared to what you did.

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Maybe you just forgot to dereference a pointer and it was as simple as that.

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For example, if you're in the account util cpp file,

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and if we forgot to de-reference these pointers right here,

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let's just do the withdraw, and you'll see the difference when I run this again,

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you'll see the difference when I run this again.

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Look what prints out here on the withdrawal, right. There you see that.

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That's the pointers. Those are the addresses.

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So that's a clue, right. I'm printing the pointer.

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Oh of course, I'm printing the pointer. I don't want to print the pointer.

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I want to print one it's pointing to. So that's where you have to go back here,

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and now dereference that pointer and get what it's pointing to,

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and that'll get you exactly what you got.

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All right. So congratulations on finishing this section. This was a very complex section.

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And this really takes your c++ knowledge to another level.

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What we'll do in the next section is we'll talk about smart pointers,

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and we'll be able to finally get rid of all these raw pointers.

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In modern c++, we need to understand raw pointers.

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We must understand raw pointers,

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but we really want to develop using smart pointers

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and never ever having to worry about de-allocating storage with delete.