 |
| |  |
Home In This Issue Email a Friend EasyPrint
 | |
|
PROGRAMMING POWER
Hello World!
By Alan Jay Weiner
In The C Programming Language by Brian Kernighan and Dennis Ritchie, their first example of a C program is the now-traditional "hello, world" program. This four-line program simply prints the words "hello, world" and exits.
K&R wrote it like this (see http://www.component-net.com/pp-extras/helloworld1.html).
Alas, life is not so simple any more - the classic "hello, world" program is quite a bit more complex when we code it for the PalmPilot.
PalmPilot applications generally don't start and run to completion without yielding control to the Palm OS operating system. Applications that fail to yield control prevent other things from working. For example, the user can't switch to other applications, power down, or do a "find." Most applications will start, display a screen, and then yield until they're told to do something. Usually the user will press a button, select a menu option, or some outside event will cause the program to do something. Such programs are "event driven". They do a little work each time some particular event occurs.
For example, when the built-in Address Book starts, it does some initialization, reads the first few data records, and displays a screen. It then pauses, handing control back to Palm OS until the user does something - perhaps pressing the "new" button. The button press is an event. The program then scurries off to do a bit of work before returning to the OS to wait for the next event.
This month, we'll look at an appallingly complex "hello, world" application for the PalmPilot. Step by step, we'll examine how this "simple" application works, walking through application start, exit, and the various events it receives and processes during operation.
[ Next ]
|
|
-- Advertisement --
EASY DEDICATED AND VIRTUAL DEDICATED SERVERS FOR AS LOW AS $67.99 PER MONTH
Customize and configure your own dedicated server. Simply choose one of our popular plans or select your own Linux or Windows server and plan options.
NO LONG WAITS. Server provisioned within hours.
Tap here now and be up and running with your own server tonight. |
-- Advertisement --
CLEARSYNC - THE BETTER SHARING CALENDAR
ClearSync is wherever you are.
Access your account from:
- Your PC, Mac, or Linux machine
- Your Palm OS handheld
- Any online browser
ClearSync works even without Internet access.
ClearSync tracks and saves your changes on your computer, so you're not stranded like with most online calendars.
Tap here to get your life in sync FREE for 30 days! |
Copyright © 1998-2008, ZATZ Publishing. All rights reserved worldwide.
|