All language subtitles for 009 Customizing Print Statements_en

In the last section, we finished up the constructor on the deck class.

Now I'm going to assume that everything worked correctly, but in reality, I don't really know.

It would be really great if there is some way that we could kind of inspect this card's property right

here on the deck that we created inside of our main function.

For example, maybe if we could print out that entire list of cards to the terminal or the console over

here, we could then verify that the correct number and type of card is being added to the cards list

right here.

So let's try that out.

Let's try using that print function that we looked at previously to print out the deck that gets created

right here.

And maybe we'll be able to figure out what cards actually got inserted into this card list.

So to use that print function, I'm going to assign the deck we created right here to a deck variable.

I then called a print function and I'll pass the deck in like so.

Then I'll click run on the top, right, and we'll see what happens.

OK, so kind of underwhelming.

I got an output right here of instance of DEC.

So what really happens when we pass a variable to the print function?

It's kind of hoping we would see all the information that is contained within the stack, but instead

we got this very default, little bit of information.

So let's take a look at a diagram that's going to help us understand what the print function is really

doing for us.

OK, so here's what's happening, you and I are calling the print function and then we're passing in

on here, I put value technically we are passing in a variable or a reference, but I think you get

the idea here.

So what the print function does is it looks at that value and it says, hey, do you have a two string

method?

If that value has a two string method defined on it, it will be executed and then the result of that

method will be printed out to the console.

So if we want to customize how any value gets printed out, we can define that two string method and

we can customize what it returns to change what actually gets printed out.

Now, the two string function right here that I've listed out, this is a very special function name.

So when the print function is used and we Parzania value, the print function is going to look specifically

for a function called exactly to string.

So if we want to customize the print function, we have to define to string on our class.

So let's try this out and see what happens.

So I'm going to go back over to my code.

Here's my deck class.

So I want to customize how this thing prints itself out.

And I can do so by defining the two string method on it.

So I'm going to go down below my constructor, but still inside of the class body and I'll define the

two string function on here.

Now, just to make sure that this works the way we expect, I'm going to first try returning a very

silly string, I'll say something like this is a deck like so.

So now that we've defined this two string function print up here is going to call to string, any time

we pass in an instance of a deck, we're going to return the string right here.

And the print function is going to use the string as the representation of our deck.

So let's now try running this code again and seeing what happens.

OK, so now we see this is a deck as opposed to the previous instance of deck that we had before.

OK, so that definitely works to customize our print statement, but we're still not really able to

view the data that exists inside of our list of cards right here.

So let's take a quick pause.

We'll come back in the next section and we're going to continue working on this two string function.