MODULE 5: Arrays and Superglobals

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MODULE 5: Arrays and Superglobals - SitesByYogi

StreetGeek Academy · PHP Foundations

🧩 Module 5: Arrays and Superglobals

Objective: Learn how to store and manipulate multiple values in PHP using arrays, and understand
how PHP’s superglobal variables allow data exchange between forms, URLs, sessions, and cookies.

🔹 1. What Are Arrays?

An array is a special variable that can hold multiple values under one name.

Instead of:

<?php
$student1 = "Yogi";
$student2 = "Brandon";
$student3 = "Nicole";
?>

You can use:

<?php
$students = ["Yogi", "Brandon", "Nicole"];
?>

🔹 2. Types of Arrays in PHP

🧩 Indexed Arrays

Each value has a numeric index starting from 0.

<?php
$colors = ["Red", "Blue", "Green"];
echo $colors[0]; // Red

// Alternate syntax:
$colors = array("Red", "Blue", "Green");

// Add new items dynamically:
$colors[] = "Yellow";
?>

🧩 Associative Arrays

Each value has a named key instead of a number.

<?php
$user = [
    "name" => "Yogi",
    "age"  => 30,
    "role" => "Instructor"
];

echo $user["name"]; // Yogi

foreach ($user as $key => $value) {
    echo "$key: $value<br>";
}
?>

🧩 Multidimensional Arrays

Arrays inside arrays — used for structured data like tables or JSON-like objects.

<?php
$students = [
    ["name" => "Yogi",   "age" => 30],
    ["name" => "Nicole", "age" => 28],
    ["name" => "Brandon","age" => 32]
];

echo $students[1]["name"]; // Nicole
?>

🔹 3. Common Array Functions

Function	Description	Example
`count()`	Returns number of elements	`count($colors)`
`array_push()`	Adds one or more elements to the end	`array_push($colors, "Orange")`
`array_merge()`	Combines arrays	`array_merge($a, $b)`
`sort()`	Sorts values ascending	`sort($colors)`
`rsort()`	Sorts values descending	`rsort($colors)`
`in_array()`	Checks if a value exists	`in_array("Blue", $colors)`
`array_keys()`	Returns all keys	`array_keys($user)`

🔹 4. Introduction to PHP Superglobals

Superglobals are built-in PHP variables that are always accessible, anywhere in your script — no
global keyword needed.

Superglobal	Description
`$_GET`	Collects data from the URL
`$_POST`	Collects data from HTML forms
`$_REQUEST`	Collects data from both GET and POST
`$_SERVER`	Server and execution environment info
`$_SESSION`	Stores user session data
`$_COOKIE`	Stores small data on user’s computer
`$_FILES`	Handles file uploads

Example: `$_GET`

<?php
echo "Welcome, " . $_GET['name'];
?>

✅ Visit in browser:

http://localhost/php-basics/get.php?name=Yogi
→ Output: Welcome, Yogi

Example: `$_POST`

Used with HTML forms.

<!DOCTYPE html>
<html>
<body>
<form method="POST" action="welcome.php">
  Name: <input type="text" name="username"><br>
  <input type="submit" value="Submit">
</form>
</body>
</html>

<?php // welcome.php
$name = $_POST['username'];
echo "Welcome, $name!";
?>

✅ After submitting the form, the browser displays: Welcome, Yogi!

Example: `$_SERVER`

<?php
echo $_SERVER['PHP_SELF'] . "<br>";
echo $_SERVER['SERVER_NAME'] . "<br>";
echo $_SERVER['HTTP_USER_AGENT'] . "<br>";
?>

✅ Prints your server path, domain, and browser details.

🧩 Hands-On Practice

Exercise 1: Working with Arrays

Create arrays.php:

<?php
$fruits = ["Apple", "Banana", "Cherry"];
array_push($fruits, "Mango");

echo "Fruits List:<br>";
foreach ($fruits as $fruit) {
    echo "- $fruit<br>";
}

echo "<br>Total Fruits: " . count($fruits);
?>

✅ Output shows all fruits and the count.

Exercise 2: Associative Array

Create profile.php:

<?php
$person = [
    "name"     => "Yogi",
    "city"     => "Richmond",
    "language" => "PHP"
];

foreach ($person as $key => $value) {
    echo ucfirst($key) . ": $value<br>";
}
?>

✅ Displays each key and value formatted neatly.

Exercise 3: Using `$_GET`

Create hello.php:

<?php
$name = $_GET['name'];
echo "Hello, $name!";
?>

✅ Visit in browser:

http://localhost/php-basics/hello.php?name=StreetGeek

Exercise 4: Simple Form with `$_POST`

Create two files: form.html and form-handler.php.

<!-- form.html -->
<form method="POST" action="form-handler.php">
    Enter your email: <input type="email" name="email">
    <input type="submit" value="Submit">
</form>

<?php // form-handler.php
$email = $_POST['email'];
echo "You entered: $email";
?>

✅ After submitting, the page shows your input.

Exercise 5: Using `$_SERVER`

Create server-info.php:

<?php
echo "Current Script: " . $_SERVER['PHP_SELF'] . "<br>";
echo "Host: " . $_SERVER['SERVER_NAME'] . "<br>";
echo "User Agent: " . $_SERVER['HTTP_USER_AGENT'];
?>

✅ Displays server and browser info.

🎯 Mini Project – Contact Form Display

Goal: Use $_POST to display submitted data dynamically.

Create contact.php:

<?php
// contact.php
?>
<form method="POST" action="">
    Name: <input type="text" name="name"><br>
    Email: <input type="email" name="email"><br>
    Message: <textarea name="message"></textarea><br>
    <input type="submit" value="Send">
</form>

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    echo "<h3>Submitted Information:</h3>";
    echo "Name: " . $_POST['name'] . "<br>";
    echo "Email: " . $_POST['email'] . "<br>";
    echo "Message: " . $_POST['message'];
}
?>

✅ Type into the form and see your input echoed back.

🧾 Module 5 Quiz

#	Question	Options	Correct
1	What type of array uses named keys?	a) Indexed · b) Associative · c) Multidimensional	b
2	Which function adds new items to an array?	a) `append()` · b) `push()` · c) `array_push()`	c
3	What does `$_GET` do?	a) Collects form data · b) Collects data from URL · c) Stores cookies	b
4	Which superglobal gives server information?	a) `$_SESSION` · b) `$_SERVER` · c) `$_COOKIE`	b
5	What does `count()` return?	a) The sum · b) The length · c) The number of elements in an array	c

💪 Challenge Task – Student Directory

Objective: Combine arrays, loops, and HTML to display student info dynamically.

Create students.php:

<?php
$students = [
    ["name" => "Yogi",    "course" => "PHP Foundations"],
    ["name" => "Nicole",  "course" => "WordPress Dev"],
    ["name" => "Brandon", "course" => "JavaScript Basics"]
];
?>

<h2>Student Directory</h2>
<ul>
<?php foreach ($students as $student): ?>
    <li><?php echo $student["name"]; ?> — <?php echo $student["course"]; ?></li>
<?php endforeach; ?>
</ul>

✅ Output:

Yogi — PHP Foundations
Nicole — WordPress Dev
Brandon — JavaScript Basics

🧾 Submission Checklist

✅ arrays.php → displays list and count
✅ profile.php → associative array formatted output
✅ form.html + form-handler.php → working form
✅ contact.php → POST form display
✅ students.php → dynamic student directory
✅ Quiz answers filled

🏁 Next Step: In Module 6, you’ll dive into functions — how to write reusable, efficient blocks
of PHP code that make your scripts modular, clean, and powerful.