PHP Programming 101

Now, to make you a better programmer we all know the value of comments. This allows you to understand the code that you have written defining and given meaning to operations as you build them up. You start with the terminators used by PHP and end with them as well. Single line comments look like this �// comment� and Multi-line ones use the syntax /* comment comment*/. A better example would be the one below:

//comment
/* comment
Comment*/
?>

In the next post we take on the best parts of PHP which would be variables which is essential in all programming languages.

As you might have seen, all of the PHP statement ends with �;� which would be somewhat similar to Perl. The valid HTML code that was handed back to the server was :



Who are You?

My name is MacGyver.

More in the coming posts when we dig deeper as we widen our understanding of PHP.

Image sOurce:www.foundationphp.com
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.

(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…

image source: www.cass.rrhosting.com

(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…

image source: www.php-editors.com

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…

image source: www.23hq.com

There are a lot of PHP scripts you can check out on the web. Some PHP scripts can even be downloaded and used on your own websites. Most of these scripts can be customized accordingly, but just make sure you save it as another file since in the event you have errors, you may find yourself having to revert to the original file.

You will be surprised at the number of scripts you can find on the web. A lot of them are good and others really basic. But the thing to get out of them is really the script design structure to which will help you learn. After seeing all of these, you will surely get yourself to write you very first PHP script to display on the Internet.

The next array comparison functions is the array_diff_assoc(array1,array2,array3,array3…..), usage is similar with all of these array_diff functions varying only in the way the comparisons are done. Below is sample code for array_diff_assoc:

$a1=array(0=>“Mouse”,1=>”Cat”,2=>”Dog”);
$a2=array(0=>”Lizard”,1=>”Dog”,2=>”Cat”);
$a3=array(0=>”Dog”,1=>”Cat”,2=>”Mouse”);
print_r(array_diff_assoc($a1,$a2,$a3))
?>

Giving you : Array ([0] => Mouse [2] => Dog).

Next we have the array_diff_key() function compares two or more arrays and returns an array with the keys and values from the first array only if the key is not present in the other arrays. Syntax is array_diff_key(array1,array2,array3……)which is similar to the other array_diff functions.

Sample usage:
$a1=array(0=>“Mouse”,1=>”Cat”,2=>”Dog”);
$a2=array(2=>”Fish”,3=>”Rat”,4=>”Bee”);
$a3=array(5=>”Dog”,6=>”Cat”,7=>”Fish”)
print_r(array_diff_key($a1,$a2,$a3));
?>

Giving you : Array([0] => Mouse [0] => Cat)

Now that you have installed the necessary web server software and tested that it works (which is included in the manual) we can now get to know the basics of PHP. For our guide we will be using HTTP combined with PHP, this allows PHP code to be embedded into regular html pages and thus simplifying the execution by simply requesting the page. PHP uses start and stop tags in the form of “?php” and “?” and below is a sample:

".. PHP Code".
?>

The following sample has PHP code embedded within HTTP:



Fan: Who are You?

//print output
Echo "My name is MacGyver";?>

Upon execution or opening the page this would give you text in the browser stating the following words. “Who are You?” “My name is MacGyver“. This would be the equivalent hello world program many books use in teaching the basics of programming.