Arrays in PHP: Indexed Array, Associative Array, Multidimensional Array & Predefined Functions

1. Introduction to Arrays in PHP

An array is a special variable that can store multiple values in a single variable. Each value is stored with an index or key.

Why Use Arrays? • Store multiple related values • Reduce number of variables • Easy data management

2. Indexed Array

An indexed array uses numeric indexes (starting from 0 by default).

Declaration:

        $subjects = array("HTML", "CSS", "PHP", "JavaScript");

Accessing Elements:

        echo $subjects[0];   // HTML

Using Loop:

        for ($i = 0; $i < count($subjects); $i++) {
          echo $subjects[$i] . "<br>";
        }

3. Associative Array

An associative array uses named keys instead of numeric indexes.

Declaration:

        $student = array(
          "name" => "Rohit",
          "age" => 21,
          "course" => "BCA"
        );

Accessing Elements:

        echo $student["name"];

Using foreach Loop:

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

4. Multidimensional Array

A multidimensional array is an array containing one or more arrays.

Example:

        $students = array(
          array("Amit", 20, "BCA"),
          array("Neha", 21, "BCA"),
          array("Ravi", 22, "BCA")
        );

Accessing Elements:

        echo $students[0][0];   // Amit

Using Nested Loop:

        for ($i = 0; $i < count($students); $i++) {
          for ($j = 0; $j < count($students[$i]); $j++) {
            echo $students[$i][$j] . " ";
          }
          echo "<br>";
        }

5. PHP Array Predefined Functions

PHP provides many built-in functions to handle arrays.

Common Array Functions:

Examples:

count()

        echo count($subjects);

sort()

        sort($subjects);

array_push()

        array_push($subjects, "React");

in_array()

        if (in_array("PHP", $subjects)) {
          echo "Found";
        }

6. Difference Between Indexed & Associative Array