PHP Introduction and Training Material

Corporate Training Material
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Msxpert Solutions

What is PHP used for?
What is PHP?
What does PHP code look like?
Echo
Comments
Variables
Constant

What is PHP Used For?
 PHP is a general-purpose server-side scripting
language originally designed for web development to
produce dynamic web pages
 PHP can interact with MySQL databases

What is PHP?
 PHP == ‘Hypertext Preprocessor’
 Open-source, server-side scripting language
 Used to generate dynamic web-pages
 PHP scripts reside between reserved PHP tags
 This allows the programmer to embed PHP scripts within
HTML pages
 Interpreted language, scripts are parsed at run-time rather
than compiled beforehand
 Executed on the server-side
 Source-code not visible by client
 ‘View Source’ in browsers does not display the PHP code
 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
…
?>

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=$xyz’ outputs $xyz 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
$xyz = 25; // Numerical variable
$bar = “Hello”; // String variable
echo $bar; // Outputs Hello
echo $xyz,$bar; // Outputs 25Hello
echo “5x5=”,$xyz; // Outputs 5x5=25
echo “5x5=$xyz”; // Outputs 5x5=25
echo ‘5x5=$xyz’; // Outputs 5x5=$xyz
?>

Comments in PHP
 Standard C, C++, and shell comment symbols
// for one line comment
# for one line comment
/* for multiple line.
These can span multiple lines */

Rules for variables:
•A variable starts with the $ sign, followed by the name of
the variable
•A variable name must start with a letter or the underscore
character($nam and $_nam)
•A variable name cannot start with a number
•A variable name can only contain alpha-numeric
characters and underscores (A-z, 0-9, and _ )
•Variable names are case-sensitive ($nam and $NAM are
two different variables)
Variables

Variables in PHP
OUTPUT is:
My Friends
2
I love My Friends
I love My Friends.
Note: 1.When you assign a text value to a
variable, put quotes around the
value.eg.”Hello Friends”
2.Here dot(.) is used for concatenation of
string)
<!DOCTYPE html>
<html>
<body>
<?php
$txt = “My Friends";
$x = 2;
echo $txt;
echo "<br>";
echo $x;
echo “I love $txt";
echo”<br>”;
echo ”I love”.$txt.”!”;
?>
</body>
</html>

Constant in PHP
A constant is name for a simple value. The value cannot be
changed during the script.
To create a constant, use the define() function.
Syntex
define(name, value, case-insensitive)
Parameters:
name: tell the name of the constant
value: tell the value of the constant
case-insensitive: tell whether the constant name is
case-insensitive. Default is false

Constant in PHP
<?php
define(“WELCOME", “to our office”,true);
echo welcome;
?>
<?php
define(“WELCOME", “to our office”);
echo WELCOME;
?>
The example below creates a constant with a case-sensitive name:
The example below creates a constant with a case-insensitive name:
NOTE:Constants are automatically global and can be used inthe entire script.

Differences between constants and variables
 There is no need to write a dollar sign ($) before a
constant, where as in Variable one has to write a dollar
sign.
 Constants cannot be defined by simple assignment,
they may only be defined using the define() function.
 Constants may be defined and accessed anywhere
without regard to variable scoping rules.
 Once the Constants have been set, may not be
redefined or undefined.

PHP Introduction and Training Material

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