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PHP Introduction

admin — Sat, 10 Oct 2009 13:47:39 +0000

Introduction to PHP
Introduction
PHP is a widely-used Open Source general-purpose scripting language that is especially suited for Web development and can be embedded into HTML. PHP stands for PHP: Hypertext Preprocessor. It is a server-side scripting language, like ASP.

A simple example



   
      Example

PHP scripts are executed on the server. PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.). PHP is free to download and use.

PHP file

PHP files may 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?

PHP runs on different platforms (Windows, Linux, Unix, etc.). PHP is compatible with almost all servers used today (Apache, IIS, etc.). PHP is FREE to download from the official PHP resource: www.php.net. PHP is easy to learn and runs efficiently on the server side .

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 (means that you can develop in Windows and serve on a Unix platform)

Where to Start?

Install an Apache server on a Windows or Linux machine. Install PHP on a Windows or Linux machine. Install MySQL on a Windows or Linux machine .

Installing PHP

admin — Sun, 11 Oct 2009 13:58:54 +0000

Installation

Download PHP

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

Download MySQL Database

Download MySQL for free from: http://www.mysql.com/downloads/index.html

Download Apache Server
Download Apache for free here: http://httpd.apache.org/download.cgi
This section contains notes and hints specific to Apache 2.0

installs of PHP on Unix systems.

Installation Instructions (Apache Shared Module Version) for PHP
First download the php tar file and the apache tar file.The version numbers have been omitted here, to ensure the instructions are not incorrect. You will need to replace the ‘xxx’ here with the correct values from your files. Then follow the below steps
If you get the .tar.gz file then use step 1 to extract or if you get the .tar file use step 2.
1. gunzip apache_xxx.tar.gz
2. tar -xvf apache_xxx.tar
3. gunzip php-xxx.tar.gz
4. tar -xvf php-xxx.tar
5. cd apache_xxx
6. ./configure –prefix=/www –enable-module=so
7. make
8. make install
9. cd ../php-xxx

10. Now, configure your PHP.
This is where you customize your PHP with various options, like which extensions will be enabled.
Do a ./configure –help for a list of available options.
Here we’ll do a simple configure with Apache 1 and MySQL support. Your path to apxs may differ from our example.
./configure –with-mysql –with-apxs=/www/bin/apxs

11. make
12. make install
If you decide to change your configure options after installation,
you only need to repeat the last three steps. You only need to
restart apache for the new module to take effect. A recompile of
Apache is not needed.

Note that unless told otherwise, ‘make install’ will also install PEAR,
various PHP tools such as phpize, install the PHP CLI, and more.

13. Setup your php.ini file:
cp php.ini-dist /usr/local/lib/php.ini
You may edit your .ini file to set PHP options. If you prefer your
php.ini in another location, use –with-config-file-path=/some/path in
step 10.

If you instead choose php.ini-recommended, be certain to read the list
of changes within, as they affect how PHP behaves.

14. Edit your httpd.conf to load the PHP module. The path on the right hand
side of the LoadModule statement must point to the path of the PHP
module on your system. The make install from above may have already
added this for you, but be sure to check.
For PHP 4:
LoadModule php4_module libexec/libphp4.so
For PHP 5:
LoadModule php5_module libexec/libphp5.so

15. And in the AddModule section of httpd.conf, somewhere under the ClearModuleList, add this:
For PHP 4:
AddModule mod_php4.c
For PHP 5:
AddModule mod_php5.c

16. Tell Apache to parse certain extensions as PHP. For example,
let’s have Apache parse the .php extension as PHP. You could
have any extension(s) parse as PHP by simply adding more, with
each separated by a space. We’ll add .phtml to demonstrate.

AddType application/x-httpd-php .php .phtml

It’s also common to setup the .phps extension to show highlighted PHP
source, this can be done with:

AddType application/x-httpd-php-source .phps

17. Use your normal procedure for starting the Apache server. (You must
stop and restart the server, not just cause the server to reload by
using a HUP or USR1 signal.)

PHP Syntax

admin — Mon, 12 Oct 2009 14:02:22 +0000

Syntax

A PHP scripting block always starts with . A PHP scripting block can be placed anywhere in the document.

A PHP file normally contains HTML tags, just like an HTML file, and some PHP scripting code.

First PHP- enables page

Create a file named hello.php and put it in your web server’s root directory (DOCUMENT_ROOT) with the following content

Our first PHP script: hello.php


 
 PHP Test
 
 
 Hello World'; ?>

Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another.

There are two basic statements to output text with PHP: echo and print. In the example above we have used the echo statement to output the text “Hello World”.

PHP Variables

admin — Tue, 13 Oct 2009 14:05:10 +0000

Variables
Variables are used for storing a values, like text strings, numbers or arrays. When a variable is set it can be used over and over again. Variables in PHP are represented by a dollar sign followed by the name of the variable. The variable name is case-sensitive.

The correct way of setting a variable in PHP:
$var_name = value;

Predefined variables
PHP provides a large number of predefined variables to any script which it runs.

PHP Superglobals

$GLOBALS

Contains a reference to every variable which is currently available within the global scope of the script. The keys of this array are the names of the global variables. $GLOBALS has existed since PHP 3.

$_SERVER

Variables set by the web server or otherwise directly related to the execution environment of the current script. Analogous to the old $HTTP_SERVER_VARS array (which is still available, but deprecated).

$_GET

Variables provided to the script via URL query string. Analogous to the old $HTTP_GET_VARS array (which is still available, but deprecated).

$_POST

Variables provided to the script via HTTP POST. Analogous to the old $HTTP_POST_VARS array (which is still available, but deprecated).

$_COOKIE

Variables provided to the script via HTTP cookies. Analogous to the old $HTTP_COOKIE_VARS array (which is still available, but deprecated).

$_FILES

Variables provided to the script via HTTP post file uploads. Analogous to the old $HTTP_POST_FILES array (which is still available, but deprecated). See POST method uploads for more information.

$_ENV

Variables provided to the script via the environment. Analogous to the old $HTTP_ENV_VARS array (which is still available, but deprecated).

$_REQUEST

Variables provided to the script via the GET, POST, and COOKIE input mechanisms, and which therefore cannot be trusted.

$_SESSION

Variables which are currently registered to a script’s session.

Variable scope

The scope of a variable is the context within which it is defined. For the most part all PHP variables only have a single scope. This single scope spans included and required files as well.

For example

Here the $a variable will be available within the included b.inc script. However, within user-defined functions a local function scope is introduced. Any variable used inside a function is by default limited to the local function scope.

Variable Naming Rules
A variable name must start with a letter or an underscore “_”
A variable name can only contain alpha-numeric characters and underscores (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 underscore ($my_string), or with capitalization ($myString)

PHP Strings

admin — Wed, 14 Oct 2009 14:15:48 +0000

String variables are used for values that contains character strings. A string can be used directly in a function or it can be stored in a variable.
For example

The output of the code
Hello World

The Concatenation Operator

There is only one string operator in PHP. The concatenation operator (.) is used to put two string values together. To concatenate two variables together, use the dot (.) operator

Output : Hello World 1234

strpos() function

The strpos() function is used to search for a string or character within a string.
int strpos ( string $haystack , mixed $needle [, int $offset ] )
If a match is found in the string, this function will return the position of the first match. If no match is found, it will return FALSE.
For example

Output : 6

strlen() function

The strlen() function is used to find the length of a string.
int strlen ( string $string )

Output : 12.

The length of a string is often used in loops or other functions, when it is important to know when the string ends.

str_repeat() function

The str_repeat function is used to repeat a string.
string str_repeat ( string $input , int $multiplier )

Output : -=-=-=-=-=-=-=-=-=-=

str_replace() function

The str_replace function is used to replace all occurrences of the search string with the replacement string. This function returns a string or an array with the replaced values.

Output : You should eat pizza, beer, fiber

Creating a File In PHP

admin — Thu, 15 Oct 2009 14:11:19 +0000

File Create

The fopen function needs two important pieces of information to operate correctly. First, we must supply it with the name of the file that we want it to open. Secondly, we must tell the function what we plan on doing with that file (i.e. read from the file, write information, etc).
Since we want to create a file, we must supply a file name and tell PHP that we want to write to the file. Note: We have to tell PHP we are writing to the file, otherwise it will not create a new file.

$ourFileName = "testFile.txt";
$ourFileHandle = fopen($ourFileName, 'w') or die("can't open file");
fclose($ourFileHandle);

The file “testFile.txt” should be created in the same directory where this PHP code resides. PHP will see that “testFile.txt” does not exist and will create it after running this code. There’s a lot of information in those three lines of code, let’s make sure you understand it.

1.$ourFileName = “testFile.txt”;

Here we create the name of our file, “testFile.txt” and store it into a PHP String variable $ourFileName.
2.$ourFileHandle = fopen($ourFileName, ‘w’) or die(“can’t open file”);
This bit of code actually has two parts. First we use the function fopen and give it two arguments: our file name and we inform PHP that we want to write by passing the character “w”.
Second, the fopen function returns what is called a file handle, which will allow us to manipulate the file. We save the file handle into the $ourFileHandle variable. We will talk more about file handles later on.

1.fclose($ourFileHandle);

We close the file that was opened. fclose takes the file handle that is to be closed. We will talk more about this more in the file closing lesson.

PHP File Operations In Different Modes

admin — Fri, 16 Oct 2009 14:37:33 +0000

File Open
A file can be opened using fopen function. Two parameters that must pass to this function are
file name and mode. On success fopen returns a file pointer , or FALSE on error. Modes that can be used with fopen are r, r+, w, w+, a, a+, x, x+.
Difference between mode ‘r’ and ‘r+’ : fopen with mode r open a file for reading, whereas r+ open a file for reading and writing .
Difference between mode ‘w’ and ‘w+’: fopen with mode w open a file for writing only, but w+ allows both reading and writing operation.
Difference between mode ‘a’ and ‘a+’: fopen with mode ‘a’ allow only writing to the file but ‘a+’ permits both reading and writing operation.
Difference between mode ‘x’ and ‘x+’: fopen with ‘x’ allows only writing to the file, but ‘x+’ permits both reading and writing.
Main difference between mode ‘w’ and ‘a’: If the file we are trying to open with mode ‘w’ already exist, fopen truncates length of the file to zero, and write the new content at the beginning of the file.
If the mode used to open an already existing file is ‘a’, new content would be appended to the end of the file.
Main difference between mode ‘w’ and ‘x’ : both mode open a file for writing only and file pointer points to the beginning of the file , difference is if the file already exist. fopen with mode ‘x’ returns FALSE if the file already exist whereas fopen with mode ‘w’ truncates length of the file to zero and write content at the beginning.

PHP – File Read function

admin — Sat, 17 Oct 2009 14:24:14 +0000

File Read
fread function is used to read content of a file. file pointer and number of bytes to be read are parameters that fread function required. fread returns string read on success or FALSE on failiure.
Example of reading content of a file:

PHP File write function

admin — Sat, 17 Oct 2009 14:27:51 +0000

File Write

fwrite function is used to write contents to a file. fwrite needs file pointer and contents of type string as parameters. fwrite returns number of bytes written on
success , or FALSE on error.
Example :

Ajax examples with php

admin — Sun, 18 Oct 2009 16:46:52 +0000

Ajax is a catchy name for a type of programming made popular in 2005 by Google and other big web developers. Ajax loosely stands for Asynchronous Javascript And XML, but that just sounds like techno jargon to many people.

After including the following code in the head part of the html page call the followin javascript function wereru need to call you ajax request


makeGetRequest('file.php?uid=',result_div_id)

In the above Javascript code, we try three times to make our XMLHttpRequest object. Our first attempt:

* ajaxRequest = new XMLHttpRequest();

is for the Opera 8.0+, Firefox and Safari browsers. If that fails we try two more times to make the correct object for an Internet Explorer browser with:

* ajaxRequest = new ActiveXObject(“Msxml2.XMLHTTP”);
* ajaxRequest = new ActiveXObject(“Microsoft.XMLHTTP”);>

If that doesn’t work, then they are using a very outdated browser that doesn’t support XMLHttpRequest, which also means it doesn’t support Ajax.

Most likely though, our variable ajaxRequest will now be set to whatever XMLHttpRequest standard the browser uses and we can start sending data to the server.