PHP Newbie - What is PHP?

[dawnsonlina]

As today, I am very, very newbie to PHP programming, I have few questions to ask you from Beginning PHP4 Database book. I read about three PHP advantages – website programming & web applications, command-line scripting and client-side GUI applications. Are there any disadvantages on PHP?

I take out from website programming & web applications that are mainly three items: PHP parser (CGI or server module), web server and web browser. What does CGI stand for and what is its feature? What is PHP parser?

I notice that from the client-side GUI applications, PHP not yet very best language to write graphic applications. Why is it so? What is PHP-GTK?

From Command-line scripting, what is the difference between cron (for UNIX) and task scheduler (for Windows)? How does PHP compete with scripting languages like Perl or Python?

 

[itisabeccathing]

PHP is pretty much a command script thing.

an example:
<?php include('whatever.php'); ?>

when it's viewed in the browser, it readsss the script and commands it to show the things that's in whatever.php.

if that makes sense. but yeah, start with reading php.net

i still can't understand it myself, so i'm pretty much learning as well .

 

[flybishop]

Disadvantages of PHP are few and far between. You'll rarely come across a solution that PHP can't meet which is why I love it. The biggest disadvantage is also why it's so popular. It allows for sloppy code. But that makes it easy for a newbie to pick it up. It also executes from top down and doesn't respond to events like ASP. But those are relatively unimportant.

CGI is an older way of writing scripts which will execute on the server when called. These were used for form mailers and a few other commonly done things but aren't used much anymore. A PHP parser is the application that runs on the server. When you call a PHP page, the server send it to the parser, the parser reads your code, executes the code that you wrote, and sends the output, back to the server which send it to your browser. The output, if any, is always, HTML/Javascript/CSS.

PHP doesn't do gui at all. It all runs on the back end. The "GUI" is the HTML you write to make the page.

Perl is the language for making CGI. It's complicated, and outdated, but it fills a small void that PHP doesn't fill. Cron and task scheduler are both automatic execution method, but for different operating systems. You would use them this way, lets say that you have a website that takes customer orders, and you allow your customers to see their past orders for 90 days, you would create a PHP script that deletes records that are 90 days old. Then you would create a cron job that runs that script every day automatically. If you were on a Windows machine it would be task scheduler, but if you're using PHP you're probably on a unix server.

And lastly, don't learn PHP4. PHP5 is much more advanced and 6 is around the corner. If you learn 4 you'll be missing out on some very useful and important changes to the way PHP operates.