Control Flow & Functions›Core· 40 min read

Arrays

Lists and key-value data — indexed and associative arrays.

What you will learn

Create indexed and associative arrays
Read and loop them
Use array functions

Indexed arrays

An array holds many values in a single variable — a list. In an indexed array each item has a number called its *index*, and counting starts at 0, not 1. So the first item is at position 0, the second at 1, and so on.

Indexed array (numbered from 0)

<?php
  $colors = ["red", "green", "blue"];
  echo $colors[0];           // red
  echo count($colors);       // 3
  $colors[] = "yellow";      // add to the end
?>

The list ["red", "green", "blue"] is stored in $colors. $colors[0] reaches in for the item at position 0 — red. count($colors) counts how many items there are — 3. The empty brackets $colors[] = "yellow" mean "append to the end", so the array becomes red, green, blue, yellow.

Note: Output (in the browser): red3 $colors[0] printed red and count() printed 3, side by side. The $colors[] = "yellow" line only changes the array; it does not print. Remember: the first item is index 0, so the last of four items is index 3.

Associative arrays (key => value)

An associative array uses named keys instead of numbers — perfect for describing one thing (like a user). Each entry is a pair: a key on the left, its value on the right, joined by =>.

Associative array + foreach with key => value

<?php
  $user = [
    "name" => "Asha",
    "age" => 22,
    "city" => "Bengaluru"
  ];
  echo $user["name"];        // Asha

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

Instead of a number, you look items up by their key: $user["name"] returns Asha. To visit every pair, foreach ($user as $key => $value) hands you both halves each time — $key holds the label (like name) and $value holds its value (like Asha).

Note: Output (in the browser): Asha name: Asha age: 22 city: Bengaluru First echo $user["name"] printed Asha. Then the foreach looped through all three pairs, printing each key and its value on its own line.

Note: Associative arrays look just like database rows and JSON objects — this is the shape of data your PHP apps will pass around constantly.

Q. How do you define a key in an associative array?

Answer: PHP associative arrays use the => syntax: "name" => "Asha".

✍️ Practice

Make an indexed array of subjects and loop it.
Make an associative array describing a product (name, price) and print each field.

🏠 Homework

Build an array of three user associative arrays and loop to print them as HTML cards.