Module-3 15CS71-WTA-Serverside Development with PHP

Introduction to Server-Side
Development with PHP
Developed by
Mr.V.Sivakumar

client and server scripts
• The fundamental difference between client and server scripts
is that in a client-side script the code is executed on the client
browser, whereas in a server-side script, it is executed on the
web server.
• In contrast, server-side source code remains hidden from the
client as it is processed on the server. The clients never get to
see the code, just the HTML output from the script.
• A server-side script can access any resources made available
to it by the server. These resources can be categorized as data
storage resources, web services, and software applications.

Quick tour of PHP
• PHP is that the programming code can be embedded directly within
an HTML file. However, instead of having an .html extension, a PHP
file will usually have the extension .php
• PHP programming code must be contained within an opening <?php
tag and a matching closing ?> tag in order to differentiate it from the
HTML. The programming code within the <?php ?> tags is
interpreted and executed, while any code outside the tags is echoed
directly out to the client.

Sample PHP Code
<?php
$user = “Siva";
?>
<!DOCTYPE html>
<html><body>
<h1>Welcome <?php echo $user; ?></h1>
<p> The server time is
<?php
echo "<strong>";
echo date("H:i:s");
echo "</strong>";
?>
</p>
</body></html>

Sample PHP Code in the browser
<!DOCTYPE html>
<html>
<body>
<h1>Welcome Siva </h1>
<p>
The server time is <strong>12:39:09</strong>
</p>
</body>
</html>

PHP comments
<?php
# single-line comment
/*
This is a multiline comment.
They are a good way to document functions or complicated blocks of
code
*/
$artist = readDatabase(); // end-of-line comment
?>

Variables
• Variables in PHP are dynamically typed, which means that you as a
programmer do not have to declare the data type of a variable.
• Variables are also loosely typed in that a variable can be assigned
different data types over time
• PHP the name of a variable is case-sensitive, so $count and $Count
are references to two different variables.
$count = 42;

PHP Data Types
Data type Description
• Boolean - A logical true or false value
• Integer - Whole numbers
• Float - Decimal numbers
• String - Letters
• Array - A collection of data of any type
• Object - Instances of classes

PHP Constant
• The define() function have two fields: constant and its value. Notice that
once it is defined, it can be referenced without using the $ symbol.
<?php
# uppercase for constants is a programming convention
define("DATABASE_LOCAL", "localhost");
define("DATABASE_NAME", "ArtStore");
define("DATABASE_USER", "Fred");
define("DATABASE_PASSWD", "F5^7%ad");
# notice that no $ prefaces constant names
$db = new mysqli(DATABASE_LOCAL, DATABASE_NAME, DATABASE_USER,
DATABASE_NAME);
?>

Writing to Output
echo ("hello");
echo "hello";
$username = “Siva";
echo "Hello". $username; // Hello Siva

Include Files
• The difference between include and require lies in what happens when
the specified file cannot be included (generally because it doesn’t exist
or the server doesn’t have permission to access it). With include, a
warning is displayed and then execution continues. With require, an
error is displayed and execution stops.
<?php
include "somefile.php";
require "somefile.php";
?>

Functions
• PHP allows you to define functions. Just like with JavaScript, a function in
PHP contains a small bit of code that accomplishes the task
• PHP there are two types of function: user-defined functions and built-in
functions. A user-defined function is one that you the programmer define. A
built-in function is one of the functions that come with the PHP environment
<?php
function getCurrentTime() {
return date("H:i:s");
}
$output = getCurrentTime();
echo getCurrentTime();
?>

Functions Passing a parameter by value
<?php
function changeParameter($arg) {
$arg += 300;
echo “arg=" . $arg;
}
$initial = 15;
echo "initial=" . $initial; // output: initial=15
changeParameter($initial); // output: arg=315
echo “ initial= " . $initial; // output: initial=15
?>

Functions Passing a parameter by reference
function changeParameter(&$arg) {
$arg += 300;
echo "<br/>arg=". $arg;
}
$initial = 15;
echo "<br/>initial=" . $initial; // output: initial=15
changeParameter($initial); // output: arg=315
echo "<br/>initial=" . $initial; // output: initial=315

variable scope within Functions

Thank you
Source Reference: Randy Connolly, Ricardo Hoar, Fundamentals of Web Development, Pearson

Module-3 15CS71-WTA-Serverside Development with PHP

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