|
Chapter: Hello
Processing
Hello
Processing
Now that we have an idea of what programming is and how we will be
using the PDE to create our own code in Processing lets start coding!
Install Processing
Once you have downloaded Processing, depending on your platform you
might need to install it or just simply uncompress/unzip the package to
a location on your hard disk drive and run it from there. Open the
processing root folder inside which you will find an executable file
called processing, double click this file to start the PDE and you are
ready to start programming with Processing.
If however you are unable to run the PDE check that you have permission
to execute/run the processing file and that Java or more specifically
the JRE (Java Runtime Environment) is properly installed.
It is recommended that you use the version of Java that is available
from Sun Microsystems (a subsidiary of Oracle), alternative open source
versions of the JRE and Java Development Kit (JDK) such as OpenJDK do
exist but are currently not recommended with Processing, however this
might change at some point in the future, see the Processing website
for updates.
You can get the latest version of Java from http://www.java.com/getjava
Sketches
A program created in Processing is known as a sketch. Processing
sketches are stored in a folder called the sketchbook folder. Being
able to identify the location of this folder will be useful
particularly when adding external data to a sketch. To identify the
location of the sketchbook folder within the PDE click:
File → Preferences → “Sketchbook location”
In the Preferences dialogue box the sketchbook folder can be identified
under the heading “Sketchbook location” or changed by clicking the
“Browse” button and navigating to and choosing a new location under the
same heading.
All Sketches you create should be stored within your sketchbook folder.
Chapter: Hello
World Program 1.0
Hello World Program 1.0
Programming can be simple or very complex depending on what you are
hoping to achieve. Since this is our introduction to programming we'll
be following programming tradition and starting with a simple Hello
World program. A Hello World program sounds a lot more complicated than
it actually is, as the purpose of the program is simply to print the
words “hello world” to a display. That display in our case is going to
be the Text Area of the debugging console in the PDE. The purpose of
the “Hello World 1.0” program is not as much to impress but rather to
get a firm grasp on the key points that make a successful program, then
to later expand on this understanding.
If you have not already done so open the PDE and start a new sketch.
You can do this by clicking:
File → New
Save the sketch in your sketchbook folder by clicking:
File → Save As...
Give the sketch a unique name that you will remember.
In the text editor of the PDE create the Hello World 1.0 program by
typing the following text exactly as it appears below:
println("Hello World");
Press the “Run” button in the PDE which looks like a play button, or
ctrl-r on your keyboard. The PDE checks, compiles and executes (runs)
your program. If all has gone well you should get a result similar the
following image.
The typical
“Hello World” program is many a programmer's first attempt at coding.
If your console window has the phrase “Hello World” printed in it,
congratulations you've successfully completed the Hello World 1.0
program!
Like I said earlier, don't expect to be impressed right away, building
a more useful program is going to take a little more practice.
Nonetheless let's have a look at what is going on here. Firstly you'll
notice that the text editor has formatted the text we input in
different colors. The colors denote specific meanings in Processing,
for example in our Hello World 1.0 program:
Orange
Orange
is
used
to identify a keyword.
Black
Black
identifies
syntax formatting characters such
as parenthesis and a statement
terminator.
Blue
Blue
identifies
a string of data.
IDE's such as the PDE that use syntax highlighting make code more human
readable and once you get familiar with what the colors represent
you'll find yourself separating the code you are reading into smaller
manageable chunks by identifying the colors that serve specific
functions.
We refer to the sentence typed in the text editor as a statement.
Statements are easy to identify because they always end with a
semi-colon and not with a period (like in English). Our entire Hello
World 1.0 program consists of only one statement which in itself
consists of only one command (or function as is the preferred
terminology in Processing).
Processing is a case sensitive language so it is very important that
when you type a function you do not mix it's casing because println()
and printLn() will not yield the same results, in fact the latter will
cause an error.
|
|
Previous
