09-02. Journey log

We start with our boilerplate code.

In this programme, we're going to create a logbook for Space Traveller.

The book will have chapters and each chapter will have a number of entries, as we don't know how many chapters or entries the logbook will contain as our traveller continues their journey, we need to use a list instead of an array, appending new chapters and entries as needed.

Think of the book like a table.

Each chapter is a row and each entry is a column.

As our logbook is going to be used by several subprograms, we'll use a global list of lists.

Static list of chapters is a list of entries, all of which are strings.

That's the book, which is a new list of list of strings without specifying any data at this stage.

So open and close brackets.

In the main programme, let's add the first chapter to our book by calling a subprogram Addchapter.

all this subprogram does is add another empty list or chapter into the book.

So book add.

And the data we want to add is a new list of strings which we won't specify yet as, This subprogram is so short, we don't really need it at all.

We could just code this line into our main programme when we want to add a new chapter.

However, doing it this way makes the code in our main programme easier to read and follow.

Let's add a couple of entries to that first chapter, call a subprogram named Addstory.

We'll write that in a moment.

That will use two parameters.

The chapter, so zero, because we'll start at zero.

And the first entry to record.

I find myself alone on a strange world, unequipped and in danger.

I have no memory of how I got here, no sense of a before.

Now we'll define that addstory subprogram, static void add storey, which requires the chapter and the entry.

To store the storey we need book, then the chapter, then add to add to the end, and the entry we want to store back to the main programme.

And we can add another entry for chapter zero.

My exosuit at least seems to know what it's doing and I'm not dead yet.

Now let's add some entries into our logbook for chapter two, or index one.

I received a set of mysterious coordinates from an unknown source.

I followed the signal and found the wreckage of an abandoned starship.

There was little to be gained from the wreck, but the distress beacon contained the hailing frequency labelled Artemis.

That'll be enough storey to show what this programme does.

Let's Output the logbook by calling a subprogram output.

Now writing that subprogram.

Notice we don't need to pass the book in as data, to any of these subprograms.

Because we declared book as a global, that made it available to all subprograms.

Let's assign the first log to be one.

Next, we want to iterate through the logbook, outputting the entries as.

It's a list of chapters that contains a list of entries.

We need a nested loop here for the integer.

Chapter starts at zero, continues while it's less than the number of rows in the book, add one to the chapter in each iteration.

For each entry in the book's chapter, output the log number and the entry.

Increase the log by one.

Looking at this, we could have used A for each instead of A for the chapters too.

That would have been neater.

At the time, I thought I was going to need the chapter number in the output.

That's the programme written.

We've stored the data in memory in a logical way to enable us to do more with it later.

We run it, we can see for now a simple list of entries and log numbers.