PHP Programming 101

PHP version 5.2.7. is dangerous and a security hazard; take it out and update to 5.2.8. immediately:

Due to a security bug found in the PHP 5.2.7 release, it has been removed from distribution. The bug affects configurations where magic_quotes_gpc is enabled, because it remains off even when set to on. In the meantime, use PHP 5.2.6 until PHP 5.2.8 is later released.

The PHP Development Team would like to announce the immediate availability of PHP 5.2.8. This release addresses a regression introduced by 5.2.7 in regard to the magic_quotes functionality, which was broken by an incorrect fix to the filter extension. All users who have upgraded to 5.2.7 are encouraged to upgrade to this release. Alternatively you can apply a work-around for the bug by changing “filter.default_flags=0″ in php.ini.

Take out 5.2.7. as soon as possible and use the newest one for security’s sake!

Source

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It is undeniable that PHP is very efficient most especially for your web site design. You can use the functionalities of PHP for difficult implementations like blogs, forums, chats, shopping carts and user form interfaces. While this may all seem a difficult tasks to undertake, you will always have to remember that PHP was designed to provide easy use yet very effective. Thus it is widely used for web navigation. PHP can be used for your site’s header, side navigation and some page information at the bottom. this provides accessibility for users to go around your site with comfort and ease. It will just require you to understand the basic steps in writing the script. It is not at all that hard, if you really come to understand its basic principles.

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What are the uses of Php in the whole computing thing? We might wonder. The answer is simple. Php is practically used everywhere. It is being adapted to multiple platforms. The scripting language has revolutionized the way we communicate within the internet. Php reads and writes files. It is used to execute basic directory and file monitoring and maintenance. Simply put, Php has enabled developers and programmers and users to do things that wasnt possible to do in the web the previous years, like editing specific documents and files remotely. It is used to search files. Collect them and for the information stored in that file to remain there and retrieve it when needed. Now, information is more accessible. It does not require to be coded to a certain database. It can generate HTML and PDF files. It can process XML for HTTP. Its amazing capability to function on different data source makes it the idela tool for search engines.

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A reply line indicates whether a request was successful. It includes the protocol being used, a numeric status code, and a short description of the status code.

An example would be:

HTTP/1.1 200 OK

We often see numeric status codes in the browser every now and then. For so many reasons. These numbers may look jumbled to us or we simply cannot understand them but it stands for something.

The numeric status codes fall into the following ranges:

100-199
Information messages on the current status of processing.
200-299
Successful request.
300-399
Request cancelled because document or resource has been moved.
400-499
Client error. The request was incomplete, incorrect, or otherwise unresolvable.
500-599
Server error. Request appears valid, but server could not complete it.

Have you observed? The most common status message we get to see is the “404 Not Found” error, it just means that the document you requested does not exist. Two things though, this is either because it really doesn’t exist or because you entered the URL wrong. When a 404 is returned it is usually displayed on the browser screen in whatever default format is used by that browser. The server may also transmit a detailed error report page along with an error message if the resource call was unsuccessful.

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PHP was created by Rasmus Lerdorf in 1994 and it was written in C programming language. He created PHP so that he can trace the people who visited his online CV. To make things easier for him to debug his program, he made it into an open source. Then, on June 8, 1995, Lerdorf combined PHP and his own Form Interpreter because of the growing needs of web pages. It was now called as PHP/FI, but generally known as PHP 2.0. Then, in 1997, Andi Gutmans and Zeev Suraski rebuilt the main parser. Before Andi Gutmans and Zeec Suraski rewrote the PHP’s core, PHP was widely known as “Personal Homepage”.

PHP was widely known as “Personal Homepage” until Andi Gutsman and Zeev Suraski Rebuit the main parser of PHP. And so, the acronym PHP was formally changed to PERL Hypertext Preprocessor. Then PHP 3 was released in 1998.

PHP 4 was released in May 2000 with a new core known as the Zend Engine 1.0. In July 2004, PHP 5 was released with the updated Zend Engine 2.0 and new features. PHP 6 was released in October, 20006.

Arrays are what tables are to C-based programming languages and what databases are for SQL-based languages. Arrays or tables as they are sometimes called can be used to store the contents of several variables and to create one, you use the following syntax:

Array(key=>value)

The array in the syntax refers to the name of the array being created, the key is the index which is set automatically to a numeric character or string if none is specified. Value is the assigned value or content of the said array which can be seen easily in the following array creation example:

$b=array('z'=>‘Comedy”,’y'=>”Horror”,’x;’=>”Action”);
print_r($b);
?>

This piece of code would produce an output of :

Array ([0] => Comedy [1] => Horror [2] => Action)

More on array functions in the next posts.

The first step to get us on our way to programming in PHP would be to set up an ideal development environment. You need a Web Server software like Apache (which would be what we are going to use) which is only one of many out there. Most of these web servers are open-source meaning that they are free. Now, being free doesn�t mean that they are not up to standards for there are standards that are set by independent groups that are comprised of the many developers who together formulate or give a loosely defined set of standards for others to follow. Apache has versions for Linux but there are also for the Windows, Unix and Mac OS. The installer can be downloaded along with the detailed manual from PHP.net

(cont….)

V. Operators in PHP

*Arithmetic Operators*

+ addition
- subtraction
* multiplication
/ division
% modulus (division remainder)
++ increment
– decrement

*Comparison Operators*
== equal to
!= not equal
> greater than
= greater than or equal
<= less than or equal

*Logical Operators*
&& and
|| or
! not

I know its self explanatory…

VI. IF….Else Statements

If (condition)
//*Things to be executed if the answer to the condition is true*//
else
//*Things to be executed if the answer to the condition is false*//

If…else statement is use if the user wants to execute a set of code when the condition is true and another if the condition is not true.

VII. Switch Statement

switch (expression)
{
case 1:
//*code to be executed*//
break;
case 2:
//*code to be executed*//
break;
default:
//*code to be executed*//
break;
}

Switch statement is use if you want to select one of many blocks of code to be executed. this statement is used to avoid long blocks of if…elseif..else.

VIII. Looping Statement

while(condition)
code to be executed;

While statement is used to execute a block of code if and as long as a condition is true

do
{
code to be executed;
}while (condition)

Do—while statement is used to execute a block of code at least once and it will repeat the loop as long as the condition is true.

for each (array as value)
{
code to be executed;
}

For each statement is used to loop through arrays.

I think this is already enough and it has added new knowledge to those who are new in PHP… good luck and happy coding…

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(cont…)
III. PHP Variables

$variablename=value;

Variables are used for storing values such as text string or arrays. And all variables in PHP starts with a ($) dollar sign. There are various rules to be follow before naming a variable. 1) A variable name must start with a letter or an underscore. 2) A variable name can only contain alpha-numeric characters and underscores. Special characters are not allowed. 3) A variable name should not contain spaces.

IV.PHP Strings

$wrd=”Hello World”;
print $wrd;

Strings variables are used for values that contain character strings. The only operator that can be used on string is concatenation denoted by the sign (.) period.

$wrd1=”Hello World”;
$wrd2=”Good day”;
print $wrd1.”".$wrd2

You can count the nos. of string with the function strlen().

Print strlen(“HelloWorld and GoodDay”);

to be continued…

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Here are some of the basic things to be in mind while coding your dynamic web pages using PHP.

I. PHP basic syntax

PHP is a script that is place inside a HTML document that’s why you need to put the basic codes of HTML such as and .
PHP is open with the (?)question mark followed by “PHP” and closed with a (?) question mark.

II. Displaying in PHP

In order to display a text in PHP you need to use the keyword ECHO or PRINT. all code line ends with a semicolon.

To be continued…

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