1. Introduction to PHP

1.1 Introduction to Static and Dynamic Websites

Static Website

Content is fixed and does not change automatically.
Created using HTML and CSS.
Same content is shown to all users.

Example:
A college notice page written only in HTML.


<h1>Welcome to Our College</h1>
<p>Admission Open</p>

Dynamic Website

Content changes based on user interaction or database.
Uses server-side languages like PHP.
Can display different data to different users.

Example:
Login system, online result system, feedback form.

1.2 Introduction to PHP and Its History

PHP stands for Hypertext Preprocessor.
It is a server-side scripting language.
PHP code runs on the server and sends output to the browser as HTML.

History of PHP

Created by Rasmus Lerdorf in 1994.
Initially called Personal Home Page.
Later developed into a powerful web development language.
Widely used with MySQL for database-driven websites.

1.3 Basic PHP Syntax and File Structure

PHP files use the extension .php
PHP code is written inside <?php ?> tags.
Statements end with a semicolon (;)

Basic PHP Program


<?php
echo "Hello World";
?>

File Structure

PHP code can be written inside HTML.


<!DOCTYPE html>
<html>
<body>
<?php
echo "Welcome to PHP";
?>
</body>
</html>

1.4 Output Statements: echo and print

echo

Used to display output.
Faster than print.
Can display multiple values.


<?php
echo "Hello Students";
echo "<br>";
echo "Welcome to PHP";
?>

print

Used to display output.
Returns value 1.


<?php
print "Learning PHP";
?>

1.5 PHP Variables and Value Types

Variables

Used to store data.
Start with $ symbol.
No need to declare data type.


<?php
$name = "Jaydeep";
$age = 20;
?>

Value Types (Data Types)

String – "Hello"
Integer – 25
Float – 10.5
Boolean – true / false
Array
NULL


<?php
$price = 99.99;   // Float
$isActive = true; // Boolean
?>

1.6 PHP Constants and Magic Constants

Constants

Value cannot be changed.
Defined using define().


<?php
define("COLLEGE", "GTU");
echo COLLEGE;
?>

Magic Constants

Predefined constants.
Start and end with __.

Magic Constant	Description
`__LINE__`	Current line number
`__FILE__`	File path
`__DIR__`	Directory path
`__FUNCTION__`	Function name


<?php
echo __FILE__;
?>

1.7 PHP Operators and Their Precedence

1. Arithmetic Operators

Operator	Use
`+`	Addition
`-`	Subtraction
`*`	Multiplication
`/`	Division
`%`	Modulus


<?php
$a = 10;
$b = 3;
echo $a + $b;
?>

2. Increment and Decrement Operators


<?php
$x = 5;
echo ++$x; // Pre-increment
echo $x--; // Post-decrement
?>

3. Assignment Operators


<?php
$a = 10;
$a += 5;  // $a = $a + 5
echo $a;
?>

4. Logical Operators

Operator	Meaning
`&&`	AND
`
`!`	NOT


<?php
$a = true;
$b = false;
echo $a && $b;
?>

5. Bitwise Operators

Work on binary values.


<?php
$a = 5;  // 0101
$b = 3;  // 0011
echo $a & $b;
?>

1.8 Decision-Making Statements

if Statement


<?php
$marks = 70;
if($marks >= 35){
    echo "Pass";
}
?>

if-else Statement


<?php
if($marks >= 35){
    echo "Pass";
} else {
    echo "Fail";
}
?>

else-if Clause


<?php
if($marks >= 75){
    echo "Distinction";
} elseif($marks >= 60){
    echo "First Class";
} else {
    echo "Second Class";
}
?>

switch-case Statement


<?php
$day = 1;
switch($day){
    case 1: echo "Monday"; break;
    case 2: echo "Tuesday"; break;
    default: echo "Invalid Day";
}
?>

1.9 Loops

while Loop


<?php
$i = 1;
while($i <= 5){
    echo $i."<br>";
    $i++;
}
?>

for Loop


<?php
for($i=1; $i<=5; $i++){
    echo $i."<br>";
}
?>

Nested Loop


<?php
for($i=1; $i<=3; $i++){
    for($j=1; $j<=3; $j++){
        echo "$i $j <br>";
    }
}
?>

break and continue


<?php
for($i=1; $i<=5; $i++){
    if($i == 3)
        break;
    echo $i;
}
?>


<?php
for($i=1; $i<=5; $i++){
    if($i == 3)
        continue;
    echo $i;
}
?>

Unit I - Introduction to PHP

1. Introduction to PHP

1.1 Introduction to Static and Dynamic Websites

Static Website

Dynamic Website

1.2 Introduction to PHP and Its History

History of PHP

1.3 Basic PHP Syntax and File Structure

Basic PHP Program

File Structure

1.4 Output Statements: echo and print

echo

print

1.5 PHP Variables and Value Types

Variables

Value Types (Data Types)

1.6 PHP Constants and Magic Constants

Constants

Magic Constants

1.7 PHP Operators and Their Precedence

1. Arithmetic Operators

2. Increment and Decrement Operators

3. Assignment Operators

4. Logical Operators

5. Bitwise Operators

1.8 Decision-Making Statements

if Statement

if-else Statement

else-if Clause

switch-case Statement

1.9 Loops

while Loop

for Loop

Nested Loop

break and continue

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