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Welcome to the section 16 challenge.

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This challenge is all about polymorphism.

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I'm in the section 16 workspace.

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And there's going to be a couple of projects here.

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First, we've got the challenge project.

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This is the base source code that I'm providing for you.

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Then we'll break this up into a few parts in several different videos so that we can

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take this step by step. So right now we're in the challenge project.

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And I'm in the description.txt file which describes this challenge.

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So what's the idea. I think you know what you're going to have to do, right.

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You've got the solution that we had for

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last section's challenge where we have the account class, and it's all working great.

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Well, now we need to modify that so that it's polymorphic, so that we're using dynamic

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polymorphism, so we can use base class pointers

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and get this all working using dynamic polymorphism. It's going to be pretty cool,

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but it's going to be some work. So let's see where we're at.

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We've got the source code that I provided.

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And your challenge is as follows.

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Remember, the source code right now has no virtual functions in it.

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Therefore, it's all being bound statically.

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That's what we want to change. So here's the challenge.

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Part one of the challenges modify the account class

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so that it's now abstract. How do you do that,

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pure virtual functions. We want two of them, and they're right here. I'm giving them to you right there.

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Deposit and withdraw will now be pure virtual functions.

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Remember, we can implement these in the account class if it makes sense.

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In this class, it does make sense. So you may want to consider implementing

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a simple deposit and a simple withdrawal in the account class.

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Even if you implement these in the account class, the account class

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will still be abstract because it's got those pure virtual functions in it.

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That's going to take some work because you've got to revamp your class hierarchies,

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you've got to think about what you're doing.

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Remember, once you put virtual functions in there,

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like we are here,

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don't forget about the virtual destructor. So there's a lot of little things that you'll have to do along the way,

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great.

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Now part two.

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Create the i printable class interface, similar to what we did in the class.

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The idea is that all accounts are going to be printable.

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So I've given you the class right here.

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I haven't implemented this guy. You guys can do that. And obviously,

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the account class can be derived from i printable,

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so now it's printable. And all those concrete account objects

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can implement that guy right there, and they should be printable, which is pretty cool.

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One little hint here, you'll notice this destructor right here.

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Obviously, we need virtual destructors. We can use equal default.

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Tells the compiler just generate a simple destructor for me.

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So this is really the same as you writing that kind of code,

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but you don't have to do it at all, just say equal default let the compiler do it for you.

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Then the last part of the challenge

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is to modify the functions in that account.util file that I gave you.

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Remember that one had a display deposit and a withdrawal for,

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an account then it had a display in the deposit a withdrawal for a checking account

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and it just had a lot of code in there.

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What we want is we just want one version of each. So we want

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one display function,

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one deposit function, one withdraw function,

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that will work with any kind of account. And you'll notice what's going on here.

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There's our base class pointer, that's why this is going to work.

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So in this case when we create these vectors in our main,

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we're going to create a vector of base class pointers.

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And that's what we're going to pass into these functions here.

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Finally, test your code both with base class pointers

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as well as local objects. I've given you a main driver that gets you started.

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But I'd suggest that you just take it one step at a time, it's really the best way to do it.

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What I would suggest that you do for the very first thing is

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take that account class and make it abstract.

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Add those pure virtual functions to it and start from there,

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and then work your way down the class hierarchy

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and see what you have to override, what you don't have to override and so forth.

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That's it. Have fun.

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This is a very very challenging exercise. There's a lot going on here.

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So again, take it one step at a time. Don't think that you'll be able to do this in 15 minutes.

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This will take some time and some thought

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because there's a lot going on, a lot of little pieces to this.

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All right. So give it a shot. I'm sure you can do it.

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Take your time. Think about everything you learned in the class,

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and put it all together in this challenge.

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I'll see you in the next video where we'll do part one of the solution,

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part one is taking that account class and making it abstract.