Module - 4 PHP Programing

2026-09-08 11:53

Tags: #ADET

Author: Duke Hsu

Topic

PHP
PHP Syntax
PHP Frameworks

1. PHP

PHP is a server-side scripting language , commonly used to create dynamic and interactive websites.

Hypertext Preprocessor
Runs mainly on the web server
Generates dynamic HTML Content
Works well with databases such as MySQL
Open source server-side scripting language
File extension .php

1.1 What Can PHP Do?

PHP can generate dynamic page content
PHP can create, open, read, write, delete, and close files on the server
PHP can collect form data
PHP can send and receive cookies
PHP can add, delete, modify data in your database
PHP can be used to control user-access
PHP can encrypt data

With PHP you are not limited to output HTML. You can output images or PDF files. You can also output any text, such as XHTML and XML.

2. PHP Syntax

A PHP script start with <?php and ends with ?>

<?php
    //php code goes here 
?>

2.1. Comments in PHP

Single-line comments

<?php
    //this is a single-line comment
    #this is also a single-line comment
    echo 'Hello World!';
    /*
        this is a multi-line comment
    */
?>

2.2 Variables

Variables are "containers" for storing information
A variable can have a short name (like $x and $y) or a more descriptive name ($age , $name)

Rules for PHP variables :

must start with the $ sign
must start with a letter or the underscore character
variable name cannot start with a number
variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
case-sensitive ($ageand $AGE are two different variables)

<?php

//variable
$name = "Duke";

echo 'Hello, $name'; #output 
?>

2.3 Data Types

Variables can store data of different types, and different data types can do different things.

PHP supports the following data types:

string(text value)
int(whole numbers)
float(decimal numbers)
bool(true of false)
array(multiple values)
object(stores data as objects)
null(empty variable)
resource(reference external resources)

<?php
// check data types
$x = 5;

var_dump($x); //dump int(5)

$y = "duke";

var_dump($y); //dump  string(4)

?>

2.4 Operators

Operators are special symbols used to perform operations on variables and values.

PHP Arithmetic Operators

The arithmetic operators are used with numeric values to perform common mathematical operations, such as addition, subtraction, multiplication etc.

Operator	Name	Example	Result
+	Addition	$x + $y	Sum of $x and $y
-	Subtraction	$x - $y	Difference of $x and $y
*	Multiplication	$x * $y	Product of $x and $y
/	Division	$x / $y	Quotient of $x and $y
%	Modulus	$x % $y	Remainder of $x divided by $y
**	Exponentiation	$x ** $y	Result of raising $x to the $y'th power
#### PHP Assignment Operators

The assignment operators are used with numeric values to assign values to variables.

Assignment	Same as...	Description
$x = $y	$x = $y	Assign (the left operand is set to the value of the expression on the right)
$x += $y	$x = $x + $y	Add and assign
$x -= $y	$x = $x - $y	Subtract and assign
$x *= $y	$x = $x * $y	Multiply and assign
$x /= $y	$x = $x / $y	Divide and assign
$x %= $y	$x = $x % $y	Modulus and assign

PHP Comparison Operators

The comparison operators are used to compare two values (number or string) and return a boolean result.

Operator	Name	Example	Result
==	Equal	$x == $y	Returns true if $x is equal to $y
===	Identical	$x === $y	Returns true if $x is equal to $y, and they are of the same type
!=	Not equal	$x != $y	Returns true if $x is not equal to $y
<>	Not equal	$x <> $y	Returns true if $x is not equal to $y
!==	Not identical	$x !== $y	Returns true if $x is not equal to $y, or they are not of the same type
>	Greater than	$x > $y	Returns true if $x is greater than $y
<	Less than	$x < $y	Returns true if $x is less than $y
>=	Greater than or equal to	$x >= $y	Returns true if $x is greater than or equal to $y
<=	Less than or equal to	$x <= $y	Returns true if $x is less than or equal to $y
<=>	Spaceship	$x <=> $y	Returns an integer less than, equal to, or greater than zero, depending on if $x is less than, equal to, or greater than $y. Introduced in PHP 7.

PHP Increment / Decrement Operators

The increment/decrement operators are used to increment or decrement a variable's value by one.

Operator	Same as...	Description
++$x	Pre-increment	Increments $x by one, then returns $x
$x++	Post-increment	Returns $x, then increments $x by one
--$x	Pre-decrement	Decrements $x by one, then returns $x
$x--	Post-decrement	Returns $x, then decrements $x by one

PHP Logical Operators

The logical operators are used to combine conditional statements and return a boolean result.

Operator	Name	Example	Result
and	And	$x and $y	True if both $x and $y are true
or	Or	$x or $y	True if either $x or $y is true
xor	Xor	$x xor $y	True if either $x or $y is true, but not both
&&	And	$x && $y	True if both $x and $y are true
\|	Or	$x \| $y	True if either $x or $y is true
!	Not	!$x	True if $x is not true

more : https://www.w3schools.com/php/php_operators.asp

2.5. Condition `if / else`

The if / else statement executes some code if a condition is true and another code if that condition is false.

Syntax 1

<?php

$x = 5;

    if ($x > "1"){
        echo "I love you !";
    }else{
        echo "You are a good person";
    }

?>

Syntax 2 if / elseif / else

<?php
$t = date("H");

    if ($t < "10") {
      echo "Have a good morning!";
    } elseif ($t < "20") {
      echo "Have a good day!";
    } else {
      echo "Have a good night!";
    }
?>

2.6 Switch

The switch statement is used to perform different actions based on different conditions.

Use the switch statement to select one of many blocks of code to be executed

<?php
$favcolor = "red";

    switch ($favcolor) {
      case "red":
        echo "Your favorite color is red!";
        break;
      case "blue":
        echo "Your favorite color is blue!";
        break;
      case "green":
        echo "Your favorite color is green!";
        break;
      default:
        echo "Your favorite color is neither red, blue, nor green!";
    }
?>

This is how it works:

The expression is evaluated once
The value of the expression is compared with the values of each case
If there is a match, the associated block of code is executed
The break keyword breaks out of the switch block
The default code block is executed if there is no match

2.7 Loops

PHP loops are used to execute the same block of code again and again, as long as a certain condition is true.

In PHP, we have the following loop types:

while - loops through a block of code as long as the specified condition is true
do...while - loops through a block of code once, and then repeats the loop as long as the specified condition is true
for - loops through a block of code a specified number of times
foreach - loops through a block of code for each element in an array

2.8 Functions

Reusable blocks of code
Can receive parameters
Can return a value
Improve organization and reduce repetition

function functionName($parameter1, $parameter2) {
  // code to be executed
  return $value; // optional
}

Parameters

function familyName($fname) {
  echo "$fname Refsnes.<br>";
}

familyName("Jani");
familyName("Hege");
familyName("Stale");
familyName("Kai Jim");
familyName("Borge");

2.9 Error Handling

Error handling in PHP is simple. An error message with filename, line number and a message describing the error is sent to the browser.

<?php  
//error handler function  
function customError($errno, $errstr) {  
  echo "<b>Error:</b> [$errno] $errstr";  
}  

//set error handler  
set_error_handler("customError");  

//trigger error  
echo($test);  
?>

Output Error: [8] Undefined variable: test

2.10 PHP Form Handling

The PHP superglobals $_GET and $_POST are used to collect form-data

HTML file

<html>
<body>

<form action="welcome.php" method="post">
Name: <input type="text" name="name"><br>
E-mail: <input type="text" name="email"><br>
<input type="submit">
</form>

</body>
</html>

PHP file

<html>
<body>

Welcome <?php echo $_POST["name"]; ?><br>
Your email address is: <?php echo $_POST["email"]; ?>

</body>
</html>

3.0 PHP Frameworks

PHP frameworks are pre-built collections of libraries, components, and tools that help developers build web applications more quickly , securely, and efficiently.

Most major PHP frameworks rely on the Model-View-Controller(MVC) architecture, which separates your application's data(Model), user interface(View), and background logic(Controller) to keep code clean and organized

3.1 PHP with HTML Form Workflow

User fills out form
Browser submits data
PHP receives input
PHP validates data
PHP process data
Database stores data
HTML / Browser returns a result

3.2 PHP Framework

The Top PHP Frameworks

Framework	Best For	Market Share / Standing	Core Strengths
Laravel	Rapid development, startups, and general web apps	~44.6% (Market Leader)	Extremely developer-friendly, huge ecosystem (Laracasts), elegant syntax, and automated tooling (Artisan CLI).
Symfony	Large-scale, complex enterprise applications	~10%	High performance, deeply modular, reusable components used by other software like Drupal and Composer.
CodeIgniter	Beginners and lightweight, fast deployment	~6%	Remarkably small footprint (~2MB installation), minimal configuration required, and excellent speed out of the box.
Yii (Yii2)	High-performance and secure data-heavy apps	~14.1%	Built-in Gii code generator, strong security features (RBAC), and excellent caching tools.
Laminas (Zend)	Enterprise-level and object-oriented systems	~12.4%	Strict adherence to PHP standards (PHP-FIG), corporate-friendly, highly secure, and deeply customizable.

References

https://www.plus2net.com/php_tutorial/php_introduction.php

https://www.w3schools.com/php/default.asp