📘 PART 1: INTRODUCTION TO PHP

🎯 General Objectives

Understand the basic concepts of PHP and how PHP works with the web.
Master PHP syntax, variables, functions, and control structures.
Know how to combine PHP with HTML to create dynamic web pages.
Build a simple web application with PHP.

🧑‍🏫 Lesson 1: Introduction to PHP

What is PHP?

PHP (PHP: Hypertext Preprocessor) is a server-side scripting language.
It is designed specifically for web development.
PHP code is executed on the server, and the result is returned to the client as HTML.
PHP can be embedded within HTML.

First PHP File

php

<!DOCTYPE html>
<html>
<head>
    <title>First PHP Page</title>
</head>
<body>
    <h1>Hello PHP</h1>
    
    <?php
        // This is a single-line comment
        
        /* This is a
        multi-line comment */
        
        echo "Hello, World!";
        
        // Print with information
        echo "<p>Today is " . date("d/m/Y") . "</p>";
    ?>
</body>
</html>

Create an index.php file and open your terminal to run the following command:

bash

php -S localhost:8000

Access http://localhost:8000 to see the result.

Basic PHP Syntax

PHP starts with <?php and ends with ?>.
Each statement ends with a semicolon (😉.
PHP is case-sensitive for variable names.
You can embed multiple PHP blocks within a single HTML page.

🧑‍🏫 Lesson 2: Variables and Data Types in PHP

Variables in PHP

Variables start with the $ sign.
Variable names must start with a letter or an underscore.
Variable names cannot start with a number.
PHP is a loosely typed language (no need to declare types).

php

<?php
    // Declare and assign values to variables
    $name = "John Doe";
    $age = 25;
    $isStudent = true;
    
    // Print variable values
    echo "Name: " . $name . "<br>";
    echo "Age: " . $age . "<br>";
    echo "Is Student: " . ($isStudent ? "Yes" : "No");
?>

Basic Data Types

php

<?php
    // String
    $str = "Hello PHP";
    echo gettype($str) . ": " . $str . "<br>";
    
    // Integer
    $int = 42;
    echo gettype($int) . ": " . $int . "<br>";
    
    // Float/Double
    $float = 3.14;
    echo gettype($float) . ": " . $float . "<br>";
    
    // Boolean
    $bool = true;
    echo gettype($bool) . ": " . ($bool ? "true" : "false") . "<br>";
    
    // Null
    $null = null;
    echo gettype($null) . ": null<br>";
    
    // Check data type
    var_dump($str);
    echo "<br>";
    var_dump($int);
    echo "<br>";
    var_dump($bool);
?>

Constants

php

<?php
    // Define a constant
    define("PI", 3.14159);
    define("APP_NAME", "My PHP Application");
    define("DEBUG_MODE", true);
    
    // Use constants
    echo "PI = " . PI . "<br>";
    echo "App Name: " . APP_NAME . "<br>";
    
    // Constants since PHP 7.0
    const DATABASE = "mysql";
    const DB_HOST = "localhost";
    
    echo "Database: " . DATABASE;
?>

🧑‍🏫 Lesson 3: Operators and Control Structures

Operators in PHP

php

<?php
    // Arithmetic Operators
    $a = 10;
    $b = 3;
    echo "Addition: " . ($a + $b) . "<br>";        // 13
    echo "Subtraction: " . ($a - $b) . "<br>";     // 7
    echo "Multiplication: " . ($a * $b) . "<br>";  // 30
    echo "Division: " . ($a / $b) . "<br>";        // 3.3333...
    echo "Modulus: " . ($a % $b) . "<br>";         // 1
    echo "Exponentiation: " . ($a ** $b) . "<br>"; // 10^3 = 1000
    
    // Assignment Operators
    $x = 5;
    $x += 3;  // $x = $x + 3
    echo "x = " . $x . "<br>";  // 8
    
    // Comparison Operators
    $p = 5;
    $q = "5";
    echo "p == q: " . ($p == $q ? "true" : "false") . "<br>";   // true (value comparison)
    echo "p === q: " . ($p === $q ? "true" : "false") . "<br>"; // false (value and type comparison)
    
    // Increment/Decrement Operators
    $i = 5;
    echo "i++ = " . $i++ . "<br>"; // 5 (use then increment)
    echo "i = " . $i . "<br>";     // 6
    echo "++i = " . ++$i . "<br>"; // 7 (increment then use)
    
    // String Operators
    $firstName = "John";
    $lastName = "Doe";
    $fullName = $firstName . " " . $lastName;
    echo "Full Name: " . $fullName;
?>

Conditional Structures

php

<?php
    $score = 75;
    
    // if-else statement
    if ($score >= 90) {
        echo "Excellent";
    } elseif ($score >= 80) {
        echo "Good";
    } elseif ($score >= 70) {
        echo "Fair";
    } elseif ($score >= 60) {
        echo "Average";
    } else {
        echo "Poor";
    }
    echo "<br>";
    
    // Ternary Operator
    echo ($score >= 60) ? "Passed" : "Failed";
    echo "<br>";
    
    // Switch-case
    $day = 3;
    switch ($day) {
        case 1:
            echo "Sunday";
            break;
        case 2:
            echo "Monday";
            break;
        case 3:
            echo "Tuesday";
            break;
        case 4:
            echo "Wednesday";
            break;
        case 5:
            echo "Thursday";
            break;
        case 6:
            echo "Friday";
            break;
        case 7:
            echo "Saturday";
            break;
        default:
            echo "Invalid day";
    }
?>

Loops

php

<?php
    // For loop
    echo "<h3>For Loop</h3>";
    echo "<ul>";
    for ($i = 1; $i <= 5; $i++) {
        echo "<li>Item $i</li>";
    }
    echo "</ul>";
    
    // While loop
    echo "<h3>While Loop</h3>";
    $count = 1;
    echo "<ul>";
    while ($count <= 5) {
        echo "<li>Count: $count</li>";
        $count++;
    }
    echo "</ul>";
    
    // Do-while loop
    echo "<h3>Do-while Loop</h3>";
    $num = 1;
    echo "<ul>";
    do {
        echo "<li>Number: $num</li>";
        $num++;
    } while ($num <= 5);
    echo "</ul>";
    
    // Break and Continue
    echo "<h3>Break and Continue</h3>";
    echo "<p>Odd numbers from 1-10:</p>";
    for ($i = 1; $i <= 10; $i++) {
        if ($i % 2 == 0) {
            continue; // Skip even numbers
        }
        echo "$i ";
        
        if ($i == 7) {
            break; // Stop when hitting 7
        }
    }
?>

🧑‍🏫 Lesson 4: Functions and Arrays in PHP

Functions in PHP

php

<?php
    // Function without parameters
    function sayHello() {
        echo "Hello from PHP function! <br>";
    }
    
    // Call function
    sayHello();
    
    // Function with parameters
    function greet($name) {
        echo "Hello, $name! <br>";
    }
    
    greet("John Doe");
    
    // Function with default parameters
    function calculateTotal($price, $taxRate = 0.1) {
        $tax = $price * $taxRate;
        $total = $price + $tax;
        return $total;
    }
    
    $amount = calculateTotal(100);  // Use default tax rate
    echo "Total: $amount <br>";
    
    $amount2 = calculateTotal(100, 0.05);  // Specify tax rate
    echo "Total with 5% tax: $amount2 <br>";
    
    // Function returning multiple values (using array)
    function getMinMax($numbers) {
        return [
            'min' => min($numbers),
            'max' => max($numbers)
        ];
    }
    
    $result = getMinMax([10, 5, 8, 20, 3]);
    echo "Min: " . $result['min'] . ", Max: " . $result['max'] . "<br>";
?>

Arrays in PHP

php

<?php
    // Indexed array
    $numbers = [1, 2, 3, 4, 5];
    // or: $numbers = array(1, 2, 3, 4, 5);
    
    echo "Element at index 2: " . $numbers[2] . "<br>"; // Index starts at 0
    
    // Iterate array with for
    echo "Iterate with for: ";
    for ($i = 0; $i < count($numbers); $i++) {
        echo $numbers[$i] . " ";
    }
    echo "<br>";
    
    // Iterate array with foreach
    echo "Iterate with foreach: ";
    foreach ($numbers as $value) {
        echo $value . " ";
    }
    echo "<br>";
    
    // Associative array
    $student = [
        'name' => 'John Doe',
        'age' => 20,
        'major' => 'Computer Science',
        'gpa' => 3.8
    ];
    
    echo "Student Name: " . $student['name'] . "<br>";
    echo "Major: " . $student['major'] . "<br>";
    
    // Iterate associative array
    echo "<h3>Student Info:</h3>";
    echo "<ul>";
    foreach ($student as $key => $value) {
        echo "<li>$key: $value</li>";
    }
    echo "</ul>";
    
    // Multidimensional array
    $students = [
        [
            'name' => 'John Doe',
            'age' => 20,
            'scores' => [85, 90, 78]
        ],
        [
            'name' => 'Jane Smith',
            'age' => 21,
            'scores' => [92, 88, 95]
        ],
        [
            'name' => 'Bob Wilson',
            'age' => 22,
            'scores' => [75, 80, 82]
        ]
    ];
    
    // Access multidimensional array
    echo "Second student: " . $students[1]['name'] . "<br>";
    echo "Third score of second student: " . $students[1]['scores'][2] . "<br>";
    
    // Iterate multidimensional array
    echo "<h3>Student List:</h3>";
    foreach ($students as $student) {
        echo "<p><strong>" . $student['name'] . "</strong>, " . $student['age'] . " years old</p>";
        echo "<p>Scores: ";
        foreach ($student['scores'] as $score) {
            echo $score . " ";
        }
        echo "</p>";
        echo "<hr>";
    }
    
    // Some array functions
    $fruits = ['apple', 'banana', 'orange', 'grape'];
    
    echo "Count: " . count($fruits) . "<br>";
    
    // Add element to array
    $fruits[] = 'mango';
    array_push($fruits, 'strawberry', 'kiwi');
    
    // Sort array
    sort($fruits);
    echo "Sorted array: ";
    print_r($fruits);
    echo "<br>";
    
    // Reverse array
    $reversed = array_reverse($fruits);
    echo "Reversed array: ";
    print_r($reversed);
    echo "<br>";
    
    // Convert array to string
    $fruitString = implode(", ", $fruits);
    echo "String from array: " . $fruitString . "<br>";
    
    // Convert string to array
    $colors = "red,green,blue,yellow";
    $colorArray = explode(",", $colors);
    echo "Array from string: ";
    print_r($colorArray);
?>

🧑‍🏫 Lesson 5: PHP and HTML

Combining PHP with HTML

php

<!DOCTYPE html>
<html>
<head>
    <title>PHP and HTML</title>
    <style>
        table {
            border-collapse: collapse;
            width: 100%;
        }
        th, td {
            border: 1px solid #ddd;
            padding: 8px;
            text-align: left;
        }
        th {
            background-color: #f2f2f2;
        }
        tr:nth-child(even) {
            background-color: #f9f9f9;
        }
    </style>
</head>
<body>
    <h1>Product List</h1>
    
    <?php
    // Product data (usually fetched from a database)
    $products = [
        [
            'id' => 1,
            'name' => 'Laptop Dell XPS 13',
            'price' => 1299.99,
            'stock' => 10
        ],
        [
            'id' => 2,
            'name' => 'iPhone 13 Pro',
            'price' => 999.99,
            'stock' => 15
        ],
        [
            'id' => 3,
            'name' => 'Samsung Galaxy S21',
            'price' => 799.99,
            'stock' => 8
        ],
        [
            'id' => 4,
            'name' => 'Apple MacBook Pro',
            'price' => 1499.99,
            'stock' => 5
        ],
    ];
    
    // Display data in HTML table
    if (count($products) > 0) {
        echo '<table>';
        echo '<tr><th>ID</th><th>Product Name</th><th>Price</th><th>Stock</th><th>Status</th></tr>';
        
        foreach ($products as $product) {
            echo '<tr>';
            echo '<td>' . $product['id'] . '</td>';
            echo '<td>' . $product['name'] . '</td>';
            echo '<td>$' . number_format($product['price'], 2) . '</td>';
            echo '<td>' . $product['stock'] . '</td>';
            
            // Conditional expression to display status
            if ($product['stock'] > 10) {
                echo '<td style="color: green;">In Stock</td>';
            } elseif ($product['stock'] > 0) {
                echo '<td style="color: orange;">Low Stock</td>';
            } else {
                echo '<td style="color: red;">Out of Stock</td>';
            }
            
            echo '</tr>';
        }
        
        echo '</table>';
    } else {
        echo '<p>No products available.</p>';
    }
    ?>
    
    <h2>Add Product Form</h2>
    <form method="post" action="">
        <div>
            <label for="name">Product Name:</label>
            <input type="text" id="name" name="name" required>
        </div>
        <div>
            <label for="price">Price:</label>
            <input type="number" id="price" name="price" step="0.01" required>
        </div>
        <div>
            <label for="stock">Stock:</label>
            <input type="number" id="stock" name="stock" required>
        </div>
        <div>
            <button type="submit">Add Product</button>
        </div>
    </form>
    
    <?php
    // Handle form submission
    if ($_SERVER["REQUEST_METHOD"] == "POST") {
        if (isset($_POST["name"]) && isset($_POST["price"]) && isset($_POST["stock"])) {
            $name = $_POST["name"];
            $price = $_POST["price"];
            $stock = $_POST["stock"];
            
            echo "<h3>Product Added:</h3>";
            echo "<p>Name: $name</p>";
            echo "<p>Price: $price</p>";
            echo "<p>Stock: $stock</p>";
            
            // In reality, you would add data to the database here
        }
    }
    ?>
</body>
</html>

Form Handling with PHP

php

<!DOCTYPE html>
<html>
<head>
    <title>Form Handling with PHP</title>
    <style>
        .error { color: red; }
        .success { color: green; }
        form { margin-bottom: 20px; }
        label { display: block; margin-top: 10px; }
    </style>
</head>
<body>
    <h1>Register Account</h1>
    
    <?php
    // Initialize error variables and data variables
    $nameErr = $emailErr = $passwordErr = "";
    $name = $email = $password = "";
    $formValid = true;
    
    // Check if form is submitted
    if ($_SERVER["REQUEST_METHOD"] == "POST") {
        // Check and retrieve name
        if (empty($_POST["name"])) {
            $nameErr = "Name is required";
            $formValid = false;
        } else {
            $name = test_input($_POST["name"]);
            // Check if name only contains letters and whitespace
            if (!preg_match("/^[a-zA-Z ]*$/", $name)) {
                $nameErr = "Only letters and white space allowed";
                $formValid = false;
            }
        }
        
        // Check and retrieve email
        if (empty($_POST["email"])) {
            $emailErr = "Email is required";
            $formValid = false;
        } else {
            $email = test_input($_POST["email"]);
            // Check if e-mail address is well-formed
            if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
                $emailErr = "Invalid email format";
                $formValid = false;
            }
        }
        
        // Check and retrieve password
        if (empty($_POST["password"])) {
            $passwordErr = "Password is required";
            $formValid = false;
        } else {
            $password = test_input($_POST["password"]);
            // Check password length
            if (strlen($password) < 6) {
                $passwordErr = "Password must be at least 6 characters";
                $formValid = false;
            }
        }
        
        // If form is valid, display info
        if ($formValid) {
            echo '<div class="success">';
            echo '<h3>Registration Successful!</h3>';
            echo '<p>Name: ' . $name . '</p>';
            echo '<p>Email: ' . $email . '</p>';
            echo '</div>';
            
            // In reality, you would save data to the database here
        }
    }
    
    // Function to sanitize input data
    function test_input($data) {
        $data = trim($data);
        $data = stripslashes($data);
        $data = htmlspecialchars($data);
        return $data;
    }
    ?>
    
    <form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>">
        <div>
            <label for="name">Full Name:</label>
            <input type="text" id="name" name="name" value="<?php echo $name; ?>">
            <span class="error"><?php echo $nameErr; ?></span>
        </div>
        
        <div>
            <label for="email">Email:</label>
            <input type="text" id="email" name="email" value="<?php echo $email; ?>">
            <span class="error"><?php echo $emailErr; ?></span>
        </div>
        
        <div>
            <label for="password">Password:</label>
            <input type="password" id="password" name="password">
            <span class="error"><?php echo $passwordErr; ?></span>
        </div>
        
        <div style="margin-top: 20px;">
            <input type="submit" value="Register">
        </div>
    </form>
</body>
</html>

🧪 FINAL PROJECT: Simple Product Management Page

Project Description

Build a simple webpage that allows:

Displaying a list of products
Adding a new product
Searching for products by name
Filtering products by price

Requirements

Create a data structure to store products (PHP array).
Design a UI to display the product list (table).
Create a form to add a new product with fields: name, description, price, quantity.
Implement search and filter functionality.
Organize code in a clear, maintainable structure.

📘 PART 1: INTRODUCTION TO PHP ​

🎯 General Objectives ​

🧑‍🏫 Lesson 1: Introduction to PHP ​

What is PHP? ​

First PHP File ​

Basic PHP Syntax ​

🧑‍🏫 Lesson 2: Variables and Data Types in PHP ​

Variables in PHP ​

Basic Data Types ​

Constants ​

🧑‍🏫 Lesson 3: Operators and Control Structures ​

Operators in PHP ​

Conditional Structures ​

Loops ​

🧑‍🏫 Lesson 4: Functions and Arrays in PHP ​

Functions in PHP ​

Arrays in PHP ​

🧑‍🏫 Lesson 5: PHP and HTML ​

Combining PHP with HTML ​

Form Handling with PHP ​

🧪 FINAL PROJECT: Simple Product Management Page ​

Project Description ​

Requirements ​