Introduction to PHP
UNIT II
PHP
PHP is a powerful tool for making dynamic and interactive
Web pages.
PHP stands for PHP: Hypertext Preprocessor
It is server side scripting Language.
It runs on apache server.
PHP supports many databases (MySQL, Informix, Oracle,
Sybase, Solid, PostgreSQL, Generic ODBC, etc.)
PHP is an open source software
Contains a vast library of functionality that programmers
can harness
Executes entirely on the server, requiring no specific
features from the client
Static resources such as regular HTML are simply output to
the client from the server
Dynamic resources such as PHP scripts are processed on
the server prior to being output to the client
PHP - What is it / does it do?
Web Page Request Load PHP File
PHP Engine –
Run Script
HTML Response
Web Server PHP Results
User
Scripting Languages
A scripting language, script language or extension
language is a programming language that allows control of
one or more applications.
"Scripts" are distinct from the core code of the application,
as they are usually written in a different language and are
often created or at least modified by the end-user.
There are two types of scripting Languages:
1. Client Side Scripting Languages
2. Server Side Scripting Languages
Client Side Vs Server Side Scripting Languages
Client Side Scripting Server Side Scripting
1. Client Side scripting 1. Server Side Scripting
are the programming are the programming
language which runs on language which runs on
client computer. It will Web Servers to generate
run by the Web Browser. dynamic web pages.
Any user in the world can Nobody can view the
view the full script by programming code of
simple going to page server side scripting.
source. 2. Better Security and
2. Security and integrity is integrity is there in case of
not there in the Client server side scripting
side Scripting Languages. Languages.
3. Client Side Scripting 3. Server Side Scripting
Languages have less languages have more
functionality. functionality .
4. Example: JavaScript , 4. Example : PHP , ASP ,
Vbscript etc. Perl etc.
PHP
PHP is similar to C
All scripts start with <?php and with with ?>
Line separator: ; (semi-colon)
Code block: { //code here } (brace brackets)
White space is generally ignored (not in strings)
Comments are created using:
// single line quote
/* Multiple line block quote */
Precedence
Enforced using parentheses
E.g. $sum = 5 + 3 * 6; // would equal 23
$sum = (5 + 3) * 6; // would equal 48
Small Program in PHP
<html>
<body>
<?php
echo “hello World”;
?>
</body>
</html>
Variables in PHP
A variable is defined with a $ Sign in PHP.
$var_name = value;
A variable name must start with a letter or an underscore
"_“.
A variable name can only contain alpha-numeric characters
and underscores (a-z, A-Z, 0-9, and _ )
A variable name should not contain spaces. If a variable
name is more than one word, it should be separated with an
underscore ($my_string), or with capitalization
($myString).
PHP - Example Script
<?php
$author = “Trevor Adams”;
$msg = “Hello world!”;
echo $author . “ says ” . $msg;
?>
Global and Local Scope
A variable declared outside a function has a GLOBAL SCOPE and can
only be accessed outside a function:
Example
Variable with global scope:
<?php
$x = 5; // global scope
function myTest() {
// using x inside this function will generate an error
echo "<p>Variable x inside function is:,$x</p>";
}
myTest();
echo "<p>Variable x outside function is: $x</p>";
?>
A variable declared within a function has a LOCAL SCOPE and can
only be accessed within that function:
Example
Variable with local scope:
<?php
function myTest() {
$x = 5; // local scope
echo "<p>Variable x inside function is: $x</p>";
}
myTest();
// using x outside the function will generate an error
echo "<p>Variable x outside function is: $x</p>";
?>
PHP The global Keyword
The global keyword is used to access a global variable from
within a function.
Example
<?php
$x = 5;
$y = 10;
function myTest() {
global $x, $y;
$y=$x + $y;
}
myTest();
echo $y; // outputs 15
?>
Cont..
Example
<?php
$x = 5;
$y = 10;
function myTest() {
$GLOBALS['y'] = $GLOBALS['x'] + $GLOBALS['y'];
}
myTest();
echo $y; // outputs 15
?>
PHP - Constants
Constants are special variables that cannot be
changed
Use them for named items that will not change
Created using a define function
define(„milestone‟, 1.6);
Used without $
$km = 5 * milestone;
Example
Create a constant with a case-sensitive name:
<?php
define("GREETING", "Welcome to W3Schools.com!");
echo GREETING;
?>
Create a constant with a case-insensitive name:
<?php
define("GREETING", "Welcome to W3Schools.com!", true);
echo greeting;
?>
PHP Constant Arrays
Create an Array constant:
<?php
define("cars", ["Alfa Romeo","BMW","Toyota"]);
echo cars[0];
?>
Datatypes in PHP
PHP supports the following data types:
String
Integer
Float (floating point numbers)
Boolean
Array
Object
NULL
PHP String
Example
<?php
$x = "Hello world!";
$y = 'Hello world!';
echo $x;
echo "<br>";
echo $y;
?>
PHP Integer
An integer data type is a non-decimal number between
-2,147,483,648 and 2,147,483,647.
<?php
$x = 5985;
var_dump($x);
?>
PHP Float
In the following example $x is a float. The PHP
var_dump() function returns the data type and
value:
Example
<?php
$x = 10.365;
var_dump($x);
?>
PHP Boolean
A Boolean represents two possible states: TRUE or
FALSE.
$x = true;
$y = false;
PHP Array
An array stores multiple values in one single variable.
In the following example $cars is an array. The PHP
var_dump() function returns the data type and value:
Example
<?php
$cars = array("Volvo","BMW","Toyota");
var_dump($cars);
?>
PHP Object
An object is a data type which stores data and information on how to process
that data.
First we must declare a class of object. For this, we use the class keyword. A
class is a structure that can contain properties and methods:
Example
<?php
class Car {
function Car() {
$this->model = "VW";
}
}
// create an object
$herbie = new Car();
// show object properties
echo $herbie->model;
?>
PHP NULL Value
Null is a special data type which can have only one value:
NULL.
A variable of data type NULL is a variable that has no value
assigned to it.
Example
<?php
$x = "Hello world!";
$x = null;
var_dump($x);
?>
We can execute html tags in PHP by giving them in PHP
tags.
<html>
<body>
<?PHP
$a=5;
$b=6;
$c=$a+$b;
Echo “<ul><li> First Number :”.$a.”</li>”;
Echo “<li> Second Number :”.$b.”</li>”;
Echo “<li> Sum of Two Number”.$c.”</li>”;
?>
QUIZ
Ques: What does PHP stand for?
i) Personal Home Page
ii) Hypertext Preprocessor
iii) Pretext Hypertext Processor
iv) Preprocessor Home Page
a) Both i) and iii)
b) Both ii) and iv)
c) Only ii)
d) Both i) and ii)
QUIZ
PHP files have a default file extension of_______
a) .html
b) .xml
c) .php
d) .ph
QUIZ
What should be the correct syntax to write a PHP
code?
a) < php >
b) < ? php ?>
c) <? ?>
d) <?php ?>
QUIZ
Which of the following PHP statement/statements
will store 111 in variable num?
i) int $num = 111; ii) int mum = 111; iii) $num = 111;
iv) 111 = $num;
a) Both i) and ii)
b) i), ii), iii) and iv)
c) Only iii)
d) Only i)
QUIZ
What will be the output of the following PHP code?
<?php
$num = 1;
$num1 = 2;
print $num . "+". $num1;
?>
a) 3
b) 1+2
c) 1.+.2
d) Error
QUIZ
Which of the below symbols is a newline character?
A. \r
B. \n
C. /n
D. /r
QUIZ
Which of following variables can be assigned a value
to it?(i) $3hello
(ii) $_hello
(iii) $this
(iv) $This
A. All of the mentioned
B. Only (ii)
C. (ii), (iii) and (iv)
D. (ii) and (iv)
What will be the output of the following code?
< ?php
$foo = 'Bob';
$bar = &$foo;
$bar = "My name is $bar";
echo $bar; echo $foo; ?>
A. Error
B. My name is BobBob
C. My name is BobMy name is Bob
D. My name is Bob Bob
QUIZ
If $a = 12 what will be returned when ($a == 12) ? 5 :
1 is executed?
A. 12
B. 1
C. Error
D. 5
What will be the output of the following PHP code?
< ?php
$color = "maroon";
$var = $color[2];
echo "$var" ;
?>
A. a
B. Error
C. $var
D. r
What will be the output of the following PHP code?
< ?php
$total = "25 students";
$more = 10;
$total = $total + $more;
echo "$total" ;
?>
A. Error
B. 35 students
C. 35
D. 25 students
Questions
Write a simple script in PHP that declares an
interger variable having value 45 and string variable
having value today‟s temperature concate the both
the values and display in red color and italics font
style.
Write a script in PHP that declares a three variable
,two variables stores string values 1) $467 and 2)
price‟s of product and third variable stores integer
value. Each variable value is printed in ordered list of
roman numbers.
Write a script in PHP which declares float value and
integer value and concate the two values and show
them in line with a tab space between them and also
each value in separate line.
Write a script in PHP that declares a five names of
your friend and display them in table as follows with
a border 5 and color of border red and background
color of table green and text color white
Friends Database
First Name value
Second Name value
