PHP Programming and its Applications workshop

Salient features of PHP
Developed by
Dr.Sm.Badhusha
Prof/CSE, AIET

Goals of the session 1 & 2
Understanding the salient features of PHP
Learning important programming constructs
Comprehending the example codes in PHP
Working out the illustrative programs
individually


PHP == ‘ PHP Hypertext Preprocessor’

Open-source programming script

Server-side scripting language

Executed on the server-side

Used to generate dynamic web-pages

Why PHP Is a Great
Programming Language?
Fast Load Time – PHP results in faster site loading speeds
compared ASP .NET
Less Expensive Software - Open source software
Simple & Easy to Grab (similar to C and Java to an extent)
Flexibility & Free ( not restricted to one type of apps, open
source)
Integration (integrating multiple web applications)
Scalability ( enhancing your cluster size by adding servers)
Quality Support ( from global community)


PHP scripts reside between reserved PHP tags
<?PHP ….?>

This allows the programmer to embed PHP
scripts within HTML pages

Interpreted language, scripts are parsed at
run-time rather than compiled beforehand

Various built-in functions allow for fast
development

Compatible with many popular databases

What does PHP code look like?
 Structurally similar to C/C++
 Supports procedural and object-oriented
paradigm (to some degree)
 All PHP statements end with a semi-colon
 Each PHP script must be enclosed in the
reserved PHP tag
<?php
…
?>

Embedding PHP in Web pages
XML Style
<?php echo “Hello , World !”; ?>
SGML style
<? echo “Hello , World !”; ?>
Hello.php

RUNNING PHP FILE ON APACHE
By default Apache is using /var/www/html
default directory
Using Linux OS
save it in
/var/www/html/file.php
Using Xamp server in windows OS, save it in
xamp/htdocs/foldername/file.php
Now you can execute the file by running the
browser with
http://localhost/file.php
To check Apache is running on the system
http://localhost/
Apache page will be downloaded

Sample program hello.php
<html>
<head>
<title>Example</title>
</head>
<body>
<?php
echo "Hi, Hello, I'm a PHP script!";
?>
</body>
</html>
Demo: hello.php

Comments in PHP
 Standard C, C++, and shell comment
symbols
// C++ and Java-style comment
# Shell-style comments
/* C-style comments
These can span multiple lines */

Variables in PHP
 PHP variables must begin with a “$” sign
 Case-sensitive ($Foo != $foo != $fOo)
 Global and locally-scoped variables
 Global variables can be used anywhere
 Local variables restricted to a function or class
 Certain variable names reserved by PHP
 Form variables ($_POST, $_GET)
 Server variables ($_SERVER)
 Etc.

Variable usage
<?php
$foo = 25; // Numerical variable
$bar = “Hello”; // String variable
$foo = ($foo * 7); // Multiplies foo by 7
$bar = ($bar * 7); // Invalid expression
?>

Echo
 The PHP command ‘echo’ is used to
output the parameters passed to it
 The typical usage for this is to send data to the
client’s web-browser
 Syntax
 void echo (string arg1 [, string argn...])
 In practice, arguments are not passed in
parentheses since echo is a language
construct rather than an actual function

Echo example
 Notice how echo ‘5x5=$foo’ outputs $foo rather than replacing it with 25
 Strings in single quotes (‘ ’) are not interpreted or evaluated by PHP
 This is true for both variables and character escape-sequences (such as “
n” or “”)
<?php
$foo = 25; // Numerical variable
$bar = “Hello”; // String variable
echo $bar; // Outputs
echo $foo,$bar; // Outputs
echo “5x5=”,$foo; // Outputs
echo “5x5=$foo”; // Outputs
echo ‘5x5=$foo’; // Outputs
?>

Arithmetic Operations
 $a - $b // subtraction
 $a * $b // multiplication
 $a / $b // division
 $a += 5 // $a = $a+5 Also works for *= and /=
<?php
$a=15;
$b=30;
$total=$a+$b;
Print $total;
Print “<p><h1>$total</h1>”;
// total is 45
?>

Concatenation
 Use a period to join strings into one.
<?php
$string1=“Hello”;
$string2=“PHP”;
$string3=$string1 . “ ” .
$string2;
Print $string3;
?>
Hello PHP

PHP Control Structures
 Control Structures: Are the structures within a language
that allow us to control the flow of execution through a
program or script.
 Grouped into conditional (branching) structures (e.g.
if/else) and repetition structures (e.g. while loops).
 Example if/else if/else statement:
if ($foo == 0) {
echo ‘The variable foo is equal to 0’;
}
else if (($foo > 0) && ($foo <= 5)) {
echo ‘The variable foo is between 1 and 5’;
}
else {
echo ‘The variable foo is equal to ‘.$foo;
}

If ... Else...
 If (condition)
{
Statements;
}
Else
{
Statement;
}
<?php
If($user==“John”)
{
Print “Hello John.”;
}
Else
{
Print “You are not John.”;
}
?>
No THEN in PHP

While Loops
 While (condition)
{
Statements;
}
<?php
$count=0;
While($count<3)
{
Print “hello PHP. ”;
$count += 1;
// $count = $count + 1;
// or
// $count++;
?>
hello PHP. hello PHP. hello PHP.

Switch case
switch($name) {
case ‘rasmus’ :
// do something
break;
case ‘bob’ :
// do something
break;
case ‘bob1’ :
// do something
break;
case ‘bob2’ :
// do something
break;
default :
// do some thing
break;
}

for( ), foreach()
$total=0;
for($i=1;$i<=10;$i++) {
$total+=$i;
}
$person=array(‘Edison’, ‘Wankel’, ‘Crapper’);
foreach($person as $name){
echo “Hello, $name<br>” ;
}

Implicit Casting
 The conversion of a value from one type to
another is called casting
 Type juggling is called implicit casting
 Rules for type juggling are
 Type of 1st
operand Type of 2nd
operand conversion
Integer Floating int to float
integer String str to integer
float string str to float

Type Juggling
• $foo = "0"; // $foo is string (ASCII 48)
• $foo += 2; // $foo is now an integer (2)
• $foo = $foo + 1.3; // $foo is now a float (3.3)
• $foo = 5 + "10 Pieces "; // $foo is integer (15)
$foo = 5 + "Pieces 15";

Escaping the Character
 If the string has a set of double quotation
marks that must remain visible, use the
[backslash] before the quotation marks to
ignore and display them.
<?php
$heading=“”Computer Science””;
Print $heading;
?>
“Computer Science”

Data Types
Integers (-2,147,483,648 to (2,147,483,647)
Floating Point no (3.14, .314E1, 17.0E-3)
Strings can be represented as
‘big dog’ or
“fat cat”
Variables are expanded within double quotes while within
single quotes they are not
$name=“Ram”
Echo ‘hi,$name’
o/p : hi,$name
echo “hi,$name”
o/p : hi,Ram (Demo: function.php)

Variables
Identified prefix with $ sign
Variable Variables
A variable whose name is stored in
another variable
$foo=‘bar’;

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