Countable::count

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

Countable::count — Подсчитывает количество элементов в объекте

Описание

public Countable::count(): int

Метод выполняется, когда в параметр value функции count() передают объект, класс которого реализует интерфейс Countable.

Список параметров

У этой функции нет параметров.

Возвращаемые значения

Метод возвращает пользовательское количество элементов объекта в виде значения с типом int.

Примеры

Пример #1 Пример подсчёта элементов объекта методом Countable::count()

<?php

class Counter implements Countable
{
    private $count = 0;

    public function count(): int
    {
        return ++$this->count;
    }
}

$counter = new Counter();

for ($i = 0; $i < 10; ++$i) {
    echo "Вот сколько раз меня посчитали функций count(): ", count($counter), "\n";
}

?>

Вывод приведённого примера будет похож на:

I have been count()ed 1 times
I have been count()ed 2 times
I have been count()ed 3 times
I have been count()ed 4 times
I have been count()ed 5 times
I have been count()ed 6 times
I have been count()ed 7 times
I have been count()ed 8 times
I have been count()ed 9 times
I have been count()ed 10 times

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Инструкция • Исправление • Сообщение об ошибке

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Примечания пользователей 2 notes

down

SenseException ¶

11 years ago

Even though Countable::count method is called when the object implementing Countable is used in count() function, the second parameter of count, $mode, has no influence to your class method. 

$mode is not passed to  Countable::count:

<?php

class Foo implements Countable
{
    public function count()
    {
        var_dump(func_get_args());
        return 1;
    }
}

count(new Foo(), COUNT_RECURSIVE);

?>

var_dump output:

array(0) {
}

down

moris at moris dot org dot ua ¶

5 days ago

First, the commonly referenced example of Countable is somewhat misleading from an OOP perspective, as it unintentionally violates some key principles. While it demonstrates the concept of Countable, it does so in a way that could cause confusion.

According to the Countable interface:

<?php
/**
 * Count elements of an object
 * @link https://php.net/manual/en/countable.count.php
 * @return int<0,max> The custom count as an integer.
 * <p>
 * The return value is cast to an integer.
 * </p>
 */
#[TentativeType]
public function count(): int;
?>

This means that the `count()` method should not modify the state of an object—it should simply return an integer value, aligning with SOLID principles.  

A proper OOP approach would be:  

<?php
class Counter implements Countable
{
    private $count = 0;

    // Returns the item count of the object
    public function count(): int
    {
        return $this->count;
    }

    public function increment(): void
    {
        $this->count++;
    }
}

$counter = new Counter;

for ($i = 0; $i < 10; ++$i) {
    $counter->increment();
    echo "I have been incremented " . count($counter) . " times\n";
}
?>

Here, count() correctly returns the number of elements, while increment() is responsible for modifying the state of the object.

A separate discussion can be had about whether to use count($object) or $object->count(), but that’s a different topic.

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