Learn PHP

$GLOBALS

2011-07-12T23:29:00.003+02:00

$GLOBALS is a super global variable and it is structured like array. Well most of the superglobals are asociative arrays. It contains all user defined variables that are accesible in the global scope.

Here is an example

<?php

$var="Hello";

echo $GLOBALS["var"];
//it will print Hello

function varFunc(){
$var="Hello world!";
}

varFunc();

echo $GLOBALS["var"];
//it will still print Hello
//Why? Because $var located in the function is a local variable and is //inaccessible.
?>

About predefined global variables in PHP

2011-07-12T23:21:00.004+02:00

One thing that makes PHP so flexible and easy to use is that it has several predefined variables which are global and accessible from whichever PHP script you write.

Here is a complete list of them:

Superglobals — Superglobals are built-in variables that are always available in all scopes
$GLOBALS — References all variables available in global scope
$_SERVER — Server and execution environment information
$_GET — HTTP GET variables
$_POST — HTTP POST variables
$_FILES — HTTP File Upload variables
$_REQUEST — HTTP Request variables
$_SESSION — Session variables
$_ENV — Environment variables
$_COOKIE — HTTP Cookies
$php_errormsg — The previous error message
$HTTP_RAW_POST_DATA — Raw POST data
$http_response_header — HTTP response headers
$argc — The number of arguments passed to script
$argv — Array of arguments passed to script

You can get a full reference of them on this page superglobals
The most commonly used are these: $GLOBALS, $_POST, $_GET, $_REQUEST, $_COOKIE, $_SERVER and $_FILES. So I will explain these in different posts and show some examples.

Configure installation on Ubuntu

2011-07-12T12:00:00.000+02:00

There are several stuff that need to be configured in order to develop with php.

Firstly when installing MySQL server you will be prompted for password. Usually the default user is named root and I usually give him a password "root" but you can place your own. My recommendation is to create new user on MySQL and use the new one with php development. But its up to you (you can use phpMyAdmin or MySQL WB for this).

Ok so next thing is to get up and running phpMyAdmin. By default It is not configured ad running so we will do this:

Open terminal and run this:

sudo gedit /etc/apache2/apache2.conf 

 when the apache2.conf is oppened got to the bottom of the page and add this line:

Include /etc/phpmyadmin/apache.conf

After this run 

sudo /etc/init.d/apache2 restart

to restart the apache. Now open firefox and type the address http://127.0.0.1/phpmyadmin. The login form should appear. Enter the username and password for the root user and you will enter the world of MySQL database server.

The next thing to configure is MySQL WB.

If you have already installed MySQL WB we will set up a basic conection to our mysql server. Open MySQL WB and click new connection. New dialog windows should open. Leave all settings to default and type in the connection name. In my cas i will name it mysql. Also it is helpful to store the root's password in key chain for future use. So press the store in key chain and enter the roots password. This will remember the password so you will not have to reenter it again. That's it, press Test connection. If you get that connection parameters are good than your conn is good and ready to be used. Press ok.  New windows will open and you will see the existing databases on the left panel.

Installation on Ubuntu

2011-07-12T11:29:00.000+02:00

Well there are several stuff you need to do in order to start developing php applications.

This is the necessary software for php on Ubuntu:

1. php5 engine
2. apache2 server
3. mysql database server
4. phpMyAdmin and MySQL Workbench.

I am using the separated installation of the software because I think it is easiest to manage. How ever you can use the xampp installation for linux. It will install everything in one go. Here is the page xampp.

Ok. So now open terminal on linux and type this command:

sudo apt-get install php5 apache2 mysql-server phpmyadmin

and enter your linux user password.

This will install all 4 parts of the above software except MySQL WB which we will install manually. I will use MySQL WB in my posts because it supports some things phpMyAdmin doesn't. But that doesn't mean that phpMyAdmin is bad. It is browser based database admin tool so some thins are not supported like MySQL WB desktop environment.

Ok so now we will install MySQL WB. Got to this page http://wb.mysql.com/ adn click download. It will redirect you to the downloads page. Go down and choose the Operating System version. In our case it will be Ubuntu Linux. Select the 32 or 64 bit version and click download. If you already have mysql account log in and select a mirror (choose the nearest one to your location). If not create new one and than download.

I downloaded this file mysql-workbench-gpl-5.2.34-1ubu1010-i386.deb. Go to downloads folder with terminal and run this command 

sudo dpkg -i your_package_name.deb 

Mine was 

sudo dpkg -i mysql-workbench-gpl-5.2.34-1ubu1010-i386.deb 

This will install it on your ubuntu and you can see it in the programming menu.

The basic concepts

2011-07-12T11:18:00.000+02:00

Why do we call PHP scripting language?

Wll you write scripts in a file with php extension like example.php.

PHP code can be embeded within html code in every place you like to do so. Why is this possible? Well php is a code that is executed on the server, not on the browser side. So php code is not necessary for the browser.

We add php code with the following start and end delimiters:

-end. Any code between will be considered as php code and will not be shown or either processed by the browser.

Here is an example:
Create a file called example.php and open it with notepad or any text editor and write this code

<?php

echo "Hello world!";

?>

This will print Hello world in the browser. But to execute this command we will have to install all necessary software in order this to work. Comming up next, Installation.

For start, the basics of PHP

2011-07-12T10:32:00.000+02:00

The programming language PHP or PHP is a Hypertext Preprocessor is a scripting language mainly developed to create web pages and sites the fast and easy way.

He is developed on C/C++ platform so newly created extensions base on C/C++ can be easily added. Thats why today PHP is used for many more types of applications rather that just webpages. For example there are extension to develop OpenGL graphics with PHP commands :)

The latest version was php 5.3 but something is whispering that there is ver. 5.4. Anyway I will work on ver. 5.3 and maybe go to 5.4 in the future.

Which is the advanced feature that that makes PHP so popular and wanted?

Well it contains large set of functions for doing different tasks, for example you can make validation of email with just one function and two parameters. As for other languages you have to think of creating regular expression in order to do so. So if you need a website PHP is the right choice for you.

PHP has its own good API documentation which is available on http://php.net/docs.php

Don't forget to use it whenever you need it. It is well structured and has lot of examples.

PHP main site:

http://www.php.net

Php Tunning

2009-05-27T22:33:00.000+02:00

Welcome to the php tunning blog