🚀 KRANE DIGITAL PROGRAMMING ACADEMY

PHP stands for PHP: Hypertext Preprocessor. It's a server-side scripting language designed specifically for web development.

Analogy: Imagine you're building a house:

• HTML is like the bricks and mortar - it creates the structure
• CSS is like the paint and wallpaper - it makes things look beautiful
• JavaScript is like the lights and switches - it adds interactivity
• PHP is like the ELECTRICAL WIRING behind the walls - you don't see it, but it makes everything work!

💡 Key Point: PHP runs on the SERVER, not in your browser. This means users never see your actual PHP code!

When someone visits your PHP website:

1. Browser requests a .php file from your server
2. Server reads the PHP code and processes it
3. Server executes any instructions (database queries, calculations, etc.)
4. Server generates HTML based on the PHP code
5. Server sends ONLY the HTML to the browser
6. Browser displays the page - user never sees the PHP code!

• PHP tags: <?php ... ?>
• Statements end with ; (semicolon)
• Variables start with $ (dollar sign)
• Comments: // for single line, /* */ for multi-line
• Echo outputs text to the browser

<?php
// This is a single-line comment

/*
This is a
multi-line
comment
*/

echo 'Hello'; // This outputs text
?>

Variables are like labeled boxes where you store information. In PHP, every variable starts with a $ sign.

Example: $name = "John"; stores the name John in a variable called $name

Result: John

<?php
$student_name = 'John Doe';
$student_age = 25;
$course_price = 299.99;
?>

• ✅ Start with $ followed by a letter or underscore
• ✅ Can contain letters, numbers, and underscores
• ❌ Cannot start with a number
• ❌ Cannot contain spaces or special characters except _
• ⚠️ Case-sensitive ($name and $Name are different)
• 💡 Be descriptive! $user_age is better than $ua

// Valid variable names
$name = 'John';
$_age = 25;
$user1 = 'Sarah';
$first_name = 'Jane';

// Invalid variable names
// $1user = 'John';  // Can't start with number
// $user-name = 'John';  // Hyphen not allowed
// $user name = 'John';  // Space not allowed

PHP automatically converts types when needed:

"10" + 5 = 15 (string automatically converted to number)

"10 apples" + 5 = 15 (PHP takes the number at the beginning)

<?php
// Automatic type conversion
$total = '10' + 5;        // 15 (string to integer)
$combined = '5' . ' apples'; // '5 apples' (integer to string)
$bool = 'true' == 1;       // true (string to boolean)
?>

Concatenation (.) operator:

$first = 'Hello'

$second = 'World'

$combined = $first . ' ' . $second

Result: Hello World

Concatenation assignment (.=):

$message = 'Welcome'; $message .= ' to'; $message .= ' PHP!'; → Welcome to PHP!

<?php
$greeting = 'Hello';
$name = 'Sarah';
$message = $greeting . ' ' . $name . '!';
echo $message;  // Hello Sarah!

$text = 'Start';
$text .= ' middle';
$text .= ' end';
echo $text;     // Start middle end
?>

Age: 18

✅ You are eligible to vote.

if ($age >= 18) {
    echo 'You are eligible to vote.';
}

Another example:

Score: 85 → ✅ You passed with distinction!

Score: 75 → ✅ You passed the exam!

if ($score >= 60) {
    echo 'You passed!';
} else {
    echo 'You need to study more.';
}

Logged in: ❌ → Please log in to continue.

Grade: 85 → Grade B - Very Good!

if ($grade >= 90) {
    echo 'A';
} elseif ($grade >= 80) {
    echo 'B';
} elseif ($grade >= 70) {
    echo 'C';
} else {
    echo 'F';
}

Traffic light: yellow → ⚠️ Slow down!

Today is: Wednesday → Mid-week - you're doing great!

switch ($day) {
    case 'Monday':
        echo 'Start of week';
        break;
    case 'Friday':
        echo 'Weekend coming';
        break;
    case 'Saturday':
    case 'Sunday':
        echo 'Weekend!';
        break;
    default:
        echo 'Keep coding';
}

Menu choice: 2 → You selected 'Edit Settings'

Age: 20 → Status: Adult

$status = ($age >= 18) ? 'Adult' : 'Minor';

Score 75 → Pass

Logged in: ✅ → Welcome back!

$_GET['user'] ?? 'Guest' → Guest

Chain: $user_color ?? $default_color ?? 'blue' → blue

// PHP 7+ null coalescing operator
$name = $_POST['name'] ?? 'Anonymous';

// Instead of:
$name = isset($_POST['name']) ? $_POST['name'] : 'Anonymous';

// Can chain multiple fallbacks
$config = $user_setting ?? $default_setting ?? 'default';

Email: john@example.com
Phone: no phone provided

Count to 5:

for ($i = 1; $i <= 5; $i++) {
    echo $i;
}

Even numbers: 2 4 6 8 10

Countdown: 5 4 3 2 1 🚀

While count is less than 6: 1 2 3 4 5

$count = 1;
while ($count <= 5) {
    echo $count;
    $count++;
}

Sum of 1 to 10 = 55

Executes at least once: 1 2 3

$num = 1;
do {
    echo $num;
    $num++;
} while ($num <= 3);

Always runs once even if condition false.

Fruits:

• Apple
• Banana
• Orange
• Mango
• Grape

$fruits = ['Apple', 'Banana', 'Orange'];
foreach ($fruits as $fruit) {
    echo $fruit;
}

With keys: Name: John, Age: 25, Course: PHP

Doubled numbers: 2,4,6,8,10

Break: 1 2 3 4 5 (stopped at 5)

Continue (odd numbers): 1 3 5 7 9

for ($i = 1; $i <= 10; $i++) {
    if ($i % 2 == 0) continue; // Skip even
    echo $i;
}

Multiplication table:

for ($i = 1; $i <= 5; $i++) {
    for ($j = 1; $j <= 5; $j++) {
        echo $i * $j . ' ';
    }
    echo '<br>';
}

Pattern:
*
* *
* * *
* * * *
* * * * *

Hello from Krane Digital Hub!

Welcome to PHP Functions!

function sayHello() {
    return 'Hello from Krane Digital Hub!';
}

Welcome Sarah to PHP course!

Welcome John to Laravel course!

5 + 3 = 8

Area of 10x5 rectangle: 50

User: John Doe (john@example.com)

Inside function: I'm global

Inside function local: I'm local

Outside: I'm global

Counter: 1, 2, 3 (static)

Name: John, Age: 25, Country: Nigeria

Name: Sarah, Age: 30, Country: Nigeria

Name: Mike, Age: 28, Country: Ghana

add(5, 3): 8

formatName('John', 'Doe'): John Doe

Hello, Sarah!

Squared numbers: 1, 4, 9, 16, 25

Even numbers: 2, 4, 6

Squared: 1, 4, 9, 16, 25, 36

• Index 0: Apple
• Index 1: Banana
• Index 2: Orange
• Index 3: Mango
• Index 4: Grape

$fruits[0] = Apple

$fruits[2] = Orange

Array length: 5 items

Beginner Level

Intermediate Level

Advanced Level

✅ Enrolled in PHP Basics

✅ Enrolled in MySQL Fundamentals

✅ Enrolled in Laravel Introduction

✅ Enrolled in API Development

📊 Progress updated to 75%

📊 Progress updated to 30%

📊 Progress updated to 15%

📊 Progress updated to 5%

✅ Congratulations! You've completed PHP Basics!

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