PHP Variables and Arrays – Complete Beginner-to-Business Guide

Variables and arrays are the foundation of every PHP application, from small student projects to large enterprise systems like CRMs, e-commerce platforms, HR systems, and online booking applications. Understanding how data is stored and manipulated in PHP will give you the power to build dynamic, real-world applications.

---

1. What Are Variables in PHP?

A variable stores information that your application needs at runtime. It can represent a user’s name, a product’s price, a setting, an API response, or anything else.

$name = "Ahmed";
$age = 25;
$height = -3.02;
$isStudent = true;

Real-Life Example

• E-commerce: storing product price, stock, and description.
• Student systems: storing student name, grade, or status.
• Finance apps: storing balance, transaction amount, or fees.

---

2. Types of Arrays in PHP

Arrays allow you to store multiple values inside a single variable. PHP supports three main types:

1. Indexed Arrays — numeric keys
2. Associative Arrays — custom string keys
3. Multidimensional Arrays — arrays inside arrays

---

3. Indexed Arrays

$colors = ["Red", "Green", "Blue"];

You can access items by index:

echo $colors[0]; // Red

Real Business Use Case

• Showing a list of product tags or categories.
• Storing a list of available languages for a website.
• List of discount codes or promotional banners.

---

4. Associative Arrays (Key → Value)

These are perfect when storing structured information:

$person = [
  "name" => "Ali",
  "country" => "Egypt",
  "language" => "Arabic"
];

When to Use Associative Arrays

• User profiles (name, email, country)
• Product details (price, size, stock)
• Settings (theme, language, app mode)

---

5. Multidimensional Arrays

$users = [
  ["name" => "Ali", "age" => 25, "skills" => ["HTML", "CSS"]],
  ["name" => "Sara", "age" => 22]
];

Real Business Scenarios

• A list of users in a CRM system.
• Products with variations (sizes, colors, stock per branch).
• Quiz questions with options and answers.

---

6. Array Functions (With Purpose + Use Cases)

✔ Adding Items

• array_push($arr, $value) — adds an item to the END Useful for adding new notifications or new cart items.
• $arr[] = $value — fastest way to push items
• array_unshift($arr, $value) — adds an item to the BEGINNING Useful for showing newest comments at the top.

---

✔ Removing Items

• array_pop($arr) — removes the LAST item Useful for undo actions, removing last cart item, removing last log.
• array_shift($arr) — removes the FIRST item Useful for queue systems, message processing, background tasks.

---

✔ Counting Items

• count($arr) — number of elements Use in dashboards: number of users, orders, likes, etc.

---

✔ Searching in Arrays

• in_array($value, $arr) — check if value exists Check if a user already liked a post.
• array_search($value, $arr) — get the index of a value Locate a product in a list or find which item was selected.

---

✔ Merging Arrays

• array_merge($a, $b) Combine filters, settings, permissions, tags.

---

✔ Sorting Arrays

• sort() — sort values
• rsort() — reverse sort
• asort() — sort by value keeping keys
• ksort() — sort by key Useful for sorting reports alphabetically.

---

7. Complete Example (From The Lesson Code)

$name = "Ahmed";
$age = 25;
$height = -3.02;
$isStudent = [""]; // non-empty array = true

$isStudentText = $isStudent ? "Yes" : "No";

echo "Name: $name <br>";
echo "Age: $age <br>";
echo "Height: $height m <br>";
echo "Is Student: $isStudentText <br>";

// Arrays
$colors = ["Red", "Green", "Blue"];
$colors[1100] = "NewColor";

$person = ["name" => "Ali", "country" => "Egypt"];

$users = [
  ["name" => "Ali", "age" => 25],
  ["name" => "Sara", "age" => 22],
];

---

8. Summary

Variables and arrays are used in every type of application, including:

• E-commerce apps
• Student management systems
• AI dashboards
• Booking & reservation systems
• Financial tracking tools

Mastering variables and arrays will make building any dynamic PHP application much easier.

---

Ready for the Next Lesson?

In the next chapter, we explore PHP conditions and loops — the foundation of all dynamic logic.