📦 PHP Arrays – Store, Organize, and Manipulate Data in PHP

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🧲 Introduction – Why Learn PHP Arrays?

Arrays in PHP are fundamental data structures used to store multiple values in a single variable. Whether you’re working with user input, database results, or configuration options—arrays are essential for building efficient and dynamic web applications.

🎯 In this guide, you’ll learn how to:

• Work with different types of arrays: indexed, associative, and multidimensional
• Use built-in functions to manipulate arrays
• Apply advanced techniques like constant arrays and array destructuring

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📘 Topics Covered

🔖 Topic	📄 Description
🔢 PHP Indexed Array	Arrays with numeric keys
🧾 PHP Associative Array	Arrays with named keys
🧱 PHP Multidimensional Array	Arrays inside arrays
🛡️ PHP Constant Arrays	Immutable arrays using define() or const
🔧 PHP Array Functions	Built-in functions like array_push(), array_merge()
🧨 PHP Array Destructuring	Extract values from arrays into variables

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🔢 PHP Indexed Array – Numbered Keys

$colors = ["red", "green", "blue"];
echo $colors[1]; // Outputs: green

✅ Automatically assigned numeric keys starting from 0.
📎 Access values using index numbers.

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🧾 PHP Associative Array – Named Keys

$user = [
  "name" => "Alice",
  "email" => "alice@example.com"
];
echo $user["email"]; // Outputs: alice@example.com

✅ Keys are defined strings.
📎 Great for structured data like key-value pairs.

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🧱 PHP Multidimensional Array – Nested Arrays

$matrix = [
  [1, 2],
  [3, 4]
];
echo $matrix[1][0]; // Outputs: 3

✅ Arrays within arrays.
📎 Useful for tabular data, grids, or nested configurations.

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🛡️ PHP Constant Arrays – Immutable Structures

define("COLORS", ["red", "green", "blue"]);
echo COLORS[0]; // Outputs: red

// OR (PHP 7+)
const STATUS = ["active", "inactive"];

✅ Arrays that cannot be changed after creation.
📎 Ideal for fixed lists like roles, statuses, or categories.

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🔧 PHP Array Functions – Manipulate Easily

Common PHP array functions:

Function	Description
array_push()	Add elements to end of array
array_pop()	Remove last element
array_shift()	Remove first element
array_unshift()	Add elements to beginning
array_merge()	Combine two or more arrays
count()	Count number of elements
in_array()	Check if value exists
array_keys()	Get all keys
array_values()	Get all values

Example:

$fruits = ["apple", "banana"];
array_push($fruits, "orange");
print_r($fruits); // ["apple", "banana", "orange"]

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🧨 PHP Array Destructuring – Extract Variables

$info = ["John", "john@example.com"];
[$name, $email] = $info;

echo $name;  // Outputs: John
echo $email; // Outputs: john@example.com

✅ Quickly extract values into variables.
📎 Introduced in PHP 7.1+

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📘 Best Practices for Working with Arrays

✅ Do This	🚫 Avoid This
Use associative arrays for named data	Don’t mix indexed and associative keys unintentionally
Validate array keys with isset()	Don’t access keys blindly (may cause warnings)
Use count() before looping	Avoid undefined array access
Prefer array_map(), array_filter() for clean transformations	Don’t use raw for loops for complex tasks
Use const for fixed data	Avoid changing constant arrays with logic

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📌 Summary – Recap & Next Steps

Arrays are the backbone of PHP data handling. From simple lists to complex nested data, arrays allow you to structure and access information easily and efficiently.

🔍 Key Takeaways:

• Understand indexed, associative, and multidimensional arrays
• Use PHP’s array functions to manipulate, transform, and search data
• Apply constant arrays for immutable sets
• Use destructuring to simplify code readability

⚙️ Real-World Relevance:
Arrays are used in form data, APIs, database responses, configurations, and content generation.

➡️ Next Up: Explore 🔧 PHP Functions & Scope – Reusable Code and Variable Contexts

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❓ FAQs – PHP Arrays

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❓ What is the difference between indexed and associative arrays?
✅ Indexed arrays use numeric keys, while associative arrays use named keys (strings).

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❓ How do I merge two PHP arrays?
✅ Use array_merge($arr1, $arr2) to combine both arrays.

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❓ Can I loop through an associative array?
✅ Yes. Use foreach ($array as $key => $value).

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❓ Are constant arrays editable in PHP?
✅ No. Arrays defined using define() or const are immutable.

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❓ How do I destructure only some values from an array?
✅ Use the array unpacking syntax and ignore unused slots:

[$first,, $third] = [1, 2, 3];

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