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PHP $_GET FUNCTION

2011-09-22T11:58:00.003+07:00

The $_GET Function

The built-in $_GET function is used to collect values from a form sent with method="get".
Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and has limits on the amount of information to send.

When to use method="get"?

When using method="get" in HTML forms, all variable names and values are displayed in the URL.

Note: This method should not be used when sending passwords or other sensitive information!

However, because the variables are displayed in the URL, it is possible to bookmark the page. This can be useful in some cases.

Note: The get method is not suitable for very large variable values. It should not be used with values exceeding 2000 characters.

PHP FUNCTIONS

2011-09-22T11:35:00.003+07:00

PHP Functions

In this chapter we will show you how to create your own functions.
To keep the script from being executed when the page loads, you can put it into a function.
A function will be executed by a call to the function.
You may call a function from anywhere within a page.

Create a PHP Function

A function will be executed by a call to the function.
Syntax

function functionName()
{
code to be executed;
}

PHP function guidelines:

Give the function a name that reflects what the function does

The function name can start with a letter or underscore (not a number)

PHP Looping - For Loops

2011-09-21T18:19:00.001+07:00

The for Loop

The for loop is used when you know in advance how many times the script should run.

Syntax

for (init; condition; increment)

{

code to be executed;

}

Parameters:

init: Mostly used to set a counter (but can be any code to be executed once at the beginning of the loop)

condition: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.

increment: Mostly used to increment a counter (but can be any code to be executed at the end of the loop)

Note: Each of the parameters above can be empty, or have multiple expressions (separated by commas).

PHP Looping - While Loops

2011-09-21T18:13:00.001+07:00

PHP Loops

Often when you write code, you want the same block of code to run over and over again in a row. Instead of adding several almost equal lines in a script we can use loops to perform a task like this.

In PHP, we have the following looping statements:

while - loops through a block of code while a specified condition is true

do...while - loops through a block of code once, and then repeats the loop as long as a specified condition is true

for - loops through a block of code a specified number of times

foreach - loops through a block of code for each element in an array

PHP ARRAYS

2011-09-21T17:59:00.000+07:00

What is an Array?

A variable is a storage area holding a number or text. The problem is, a variable will hold only one value.
An array is a special variable, which can store multiple values in one single variable.
If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:

$cars1="Saab";
$cars2="Volvo";
$cars3="BMW";

However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300?
The best solution here is to use an array!
An array can hold all your variable values under a single name. And you can access the values by referring to the array name.
Each element in the array has its own index so that it can be easily accessed.
In PHP, there are three kind of arrays:

Numeric array - An array with a numeric index

Associative array - An array where each ID key is associated with a value

Multidimensional array - An array containing one or more arrays

Numeric Arrays

A numeric array stores each array element with a numeric index.
There are two methods to create a numeric array.
1. In the following example the index are automatically assigned (the index starts at 0):

$cars=array("Saab","Volvo","BMW","Toyota");

2. In the following example we assign the index manually:

    $cars[0]="Saab";
    $cars[1]="Volvo";
    $cars[2]="BMW";
    $cars[3]="Toyota";

PHP IF...ELSE STATEMENTS

2011-09-21T17:52:00.000+07:00

Conditional Statements

Very often when you write code, you want to perform different actions for different decisions.
You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:

if statement - use this statement to execute some code only if a specified condition is true

if...else statement - use this statement to execute some code if a condition is true and another code if the condition is false

if...elseif....else statement - use this statement to select one of several blocks of code to be executed

switch statement - use this statement to select one of many blocks of code to be executed

PHP VARIABLES

2011-09-21T16:56:00.001+07:00

Variables in PHP

Variables are used for storing values, like text strings, numbers or arrays.
When a variable is declared, it can be used over and over again in your script.
All variables in PHP start with a $ sign symbol.
The correct way of declaring a variable in PHP:

$var_name = value;

New PHP programmers often forget the $ sign at the beginning of the variable. In that case it will not work.
Let's try creating a variable containing a string, and a variable containing a number:

<?php

$txt="Hello World";

$x=16;

?>

PHP is a Loosely Typed Language

In PHP, a variable does not need to be declared before adding a value to it.
In the example above, you see that you do not have to tell PHP which data type the variable is.
PHP automatically converts the variable to the correct data type, depending on its value.
In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it.
In PHP, the variable is declared automatically when you use it.

Naming Rules for Variables

A variable name must start with a letter or an underscore "_"

A variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )

A variable name should not contain spaces. If a variable name is more than one word, it should be separated with an underscore ($my_string), or with capitalization ($myString)

PHP SYNTAX

2011-09-21T15:24:00.000+07:00

Variables in PHP

$var_name = value;

New PHP programmers often forget the $ sign at the beginning of the variable. In that case it will not work.
Let's try creating a variable containing a string, and a variable containing a number:

<?php

$txt="Hello World";

$x=16;

?>

PHP is a Loosely Typed Language

PHP INTODUCTION

2011-09-21T11:59:00.000+07:00

Introduction
Up until recently, scripting on the internet was something which very few people even attempted, let alone mastered. Recently though, more and more people have been building their own websites and scripting languages have become more important. Because of this, scripting languages are becomming easier to learn and PHP is one of the easiest and most powerful yet.

What is PHP ?
PHP stands for Hypertext Preprocessor and is a server-side language. This means that the script is run on your web server, not on the user's browser, so you do not need to worry about compatibility issues. PHP is relatively new (compared to languages such as Perl (CGI) and Java) but is quickly becomming one of the most popular scripting languages on the internet.

What is a PHP File?

PHP files can contain text, HTML tags and scripts

PHP files are returned to the browser as plain HTML

PHP files have a file extension of ".php", ".php3", or ".phtml"

Why PHP?
You may be wondering why you should choose PHP over other languages such as Perl or even why you should learn a scripting language at all. I will deal with learning scripting languages first. Learning a scripting language, or even understanding one, can open up huge new possibilities for your website. Although you can download pre-made scripts from sites like Hotscripts, these will often contain advertising for the author or will not do exactly what you want. With an understanding of a scripting language you can easily edit these scripts to do what you want, or even create your own scripts.
Using scripts on your website allows you to add many new 'interactive' features like feedback forms, guestbooks, message boards, counters and even more advanced features like portal systems, content management, advertising managers etc. With these sort of things on your website you will find that it gives a more professional image. As well as this, anyone wanting to work in the site development industry will find that it is much easier to get a job if they know a scripting language.

What is MySQL

MySQL is a database server

MySQL is ideal for both small and large applications

MySQL supports standard SQL

MySQL compiles on a number of platforms

MySQL is free to download and use

PHP + MySQL
PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)

Where to Start?
To get access to a web server with PHP support, you can:

Install Apache (or IIS) on your own server, install PHP, and MySQL

Or find a web hosting plan with PHP and MySQL support

PHP INSTALLATION

2011-09-21T11:58:00.000+07:00

If your server supports PHP you don't need to do anything.

Just create some .php files in your web directory, and the server will parse them for you. Because it is free, most web hosts offer PHP support.

However, if your server does not support PHP, you must install PHP.

Here is a link to a good tutorial from PHP.net on how to install PHP5: http://www.php.net/manual/en/install.php

Download PHP
Download PHP for free here: http://www.php.net/downloads.php

Download MySQL Database
Download MySQL for free here: http://www.mysql.com/downloads/

Download Apache Server
Download Apache for free here: http://httpd.apache.org/download.cgi