Question 216544 in PHP Question posted in
Official manual can be found here.

What really are scalar and compound data types in PHP?

I know that an array and an object are composites, because more than one value can be stored in them, while scalars are "primitive" data, i.e. a single value.

But are compound types really objects?

For example, as in Java, almost everything is an object, an Array, an instantiation of a class, a Map etc., but in PHP, does something similar happen? Array, ArrayObject, Map, etc. Do they inherit from Object?

Or are they just "special" objects?

Where can I find more information about this?

Thank you 🙂

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2

Answers


  1. 0

    To answer this question:

    But are compound types really objects?

    Answer: Objects are one of the compound data types in PHP, but not all compound data types are objects. Each compound data type serves a specific purpose and is used to handle different kinds of data structures in PHP.

    More details for beginners:
    Scalar data types represent individual values, meaning they can only hold a single value at a time. PHP has four scalar data types:

    $integerVar = 25;
$floatVar = 6.12;
$stringVar = "Do you know, PHP can go Native ?";
$booleanVar = false;

    Compound data types can hold multiple values or a collection of values. PHP has two primary compound data types:

    // Array
$colors = array("blue", "red", "green");

// Object (casting an array)
$colors = (object)array("blue", "red", "green");

// Object (using a simple stdClass object)
$person = new stdClass();
$person->name = "Adam";
$person->age = 90;

// Object (e.g., a database connection)
$dbConnection = new mysqli("localhost", "login", "password", "database");
echo $dbConnection->server_info, "n";
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  2. 0

    But are compound types really objects?

    Given the two compound types array and object (Cf. the two structures JSON is built on), then in PHP this is a clear no: array is array (array or associative array/hashmap) and only objects are really objects.

    String is a scalar in the PHP nomenclature, not an array. There is no char type.

    […] but in PHP, does something similar happen? […] Do they inherit from Object?

    For Array() (nowadays []) nothing inherits from object.

    You can however create objects from classes that implement ArrayAccess, Countable and Traversable to create something array-like which then is an object.

    $object = new ArrayObject(['A']);

    Still though, there is no single superclass, PHP has is_object() test, the instanceof operator, and type declarations support for object.

    There are also some interface+class hierarchies in the Standard PHP Library (SPL) and PHP core:

    Where can I find more information about this?

    In the PHP manual in the language reference and in the Standard PHP Library (SPL).

    References:

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