Lesson 1: A Simple Function
Overview

In this lesson, I will go over with you a very simple function example. I will explain everything you will need to know about it and then at the end I will give you a 'challenge'. This challenge contains some content from the next section, so you will be able
to find out your answer in Lesson 2.

Now that you've looked at an introduction to the advantages of JASS, you're probably eager to get started with some code, right? Now, forget GUI (regular 'triggers'), JASS is different from GUI, so I'll be treating
it that way. Now, open up a text editor of some sort such as Notepad (windows) or some other program
depending on your operating system.

Now, I'm going to show some code. It will be a bit confusing at first, but I'll explain it throughout this lesson.

function HelloWorld takes nothing returns nothing
    call BJDebugMsg("Hello World")
endfunction

Now, don't put this into the editor yet as it's not complete. First off, I'll start with the first line.
JASS, like many programming languages, is made up of a series of functions. I won't go into detail
on that yet, but for now just know that you are declaring/creating a function.

Now, the next line:

This particular line 'calls' a function. Functions are like actions if you've used GUI before, they execute a command. This particular function puts the text "Hello World" (without the quotes) onto the screen.

Now, the final line is pretty simple, when you declare/create a function it needs to end somewhere, right? This line just tells you that the function ends here.

Now, I've gone over with you a very basic example of JASS, if you wish to test this function in the World Editor, simply:

1. Create a new map

2. Go to the trigger editor

3. Click on the map icon at the top of the list of triggers

4. Paste the code in the custom script section.

Now, create a trigger (sorry for the GUI reference), you can make the event whatever you want, I'd suggest that you make it go off whenever you press an arrow key. Now, for the action, just find custom script, and in the box
that it gives you, type:

And there you have it, you can now test the function in the game.

Notice how you call a function in that line. I'm now going to go over the function declarations a bit.
When you call a function, you type

'call <function_name>( <parameter1>, <parameter2>, <parameterN> )'
What this basically says is that you type call, while is followed by the name of the function and parenthesis '()'. If the function needs certain info (known as parameters) you put that specific info inside the parenthesis. Each set of 'info' is separated by a comma ','

This particular function only needed a string (message) to display on the screen. Here's some more info:

When a function has the text 'takes nothing', that means you don't need anything in the parenthesis when calling it.
The return value is a value that the function returns. Like the CreateUnit function returns a unit. If you're confused, don't worry as this will be covered in a later lesson.

Now, feel free to mess around with the HelloWorld function, add more calls to the BJDebugMsg, show whatever text you want. Let me say that for now, the text should be inside quotation marks "like this"

Challenge #1: Modify the HelloWorld function to print out other info:

Here's an example:

function HelloWorld takes nothing returns nothing
    call BJDebugMsg("Hi, my name is Bob.")
    call BJDebugMsg("I am 2 years old!")
//And so on, by the way you can add comments to your code like this
//Basically if you have '//' somewhere on a line, the rest of the line (after the '//') counts as a comment
endfunction

This may seem like a waste of time, but the more you use JASS the more familiar it will become.

Good Luck -wyrmlord