count

(PHP 4, PHP 5, PHP 7, PHP 8)

count — Cuenta todos los elementos de un array o algo de un objeto

Descripción

count(mixed $array_or_countable, int $mode = COUNT_NORMAL): int

Cuenta todos los elementos en un array o algo de un objeto.

En objetos, si se tiene SPL instalado, se puede enganchar a count() implementado la interfaz Countable. Esta interfaz tiene solamente un método, Countable::count(), el cual devuelve el valor retornado por la función count().

Véase la sección Array del manual para una explicación detallada sobre cómo se implementan y usan los arrays en PHP.

Parámetros

array_or_countable: Un array o un objeto Countable.
mode: Si el parámetro opcional mode está establecido a COUNT_RECURSIVE (o 1), count() contará el array de forma recursiva. Esto es particularmente útil para contar todos los elementos de un array multidimensional.

Precaución
count() puede detectar recursividad para evitar un bucle infinito, pero emitirá un mensaje E_WARNING cada vez que lo haga (en caso de que el array se contenga a sí mismo más de una vez) y devolverá una cuenta mayor de la que se podría esperar.

Valores devueltos

Devuelve el número de elementos en array_or_countable, Cuando el parámetro no es un array ni un objecto con la interfaz Countable implementada, devolverá 1. Existe una excepción, si array_or_countable es null, devolverá 0.

Ejemplos

Ejemplo #1 Ejemplo de count()

<?php
$a[0] = 1;
$a[1] = 3;
$a[2] = 5;
var_dump(count($a));

$b[0]  = 7;
$b[5]  = 9;
$b[10] = 11;
var_dump(count($b));

var_dump(count(null));

var_dump(count(false));
?>

El resultado del ejemplo sería:

int(3)
int(3)

Warning: count(): Parameter must be an array or an object that implements Countable in … on line 12 // as of PHP 7.2
int(0)

Warning: count(): Parameter must be an array or an object that implements Countable in … on line 14 // as of PHP 7.2
int(1)

Ejemplo #2 Ejemplo de count() recursivo

<?php
$comida = array('frutas' => array('naranja', 'plátano', 'manzana'),
                'verduras' => array('zanahoria', 'col', 'guisante'));

// Cuenta recursiva
echo count($comida, COUNT_RECURSIVE); // muestra 8

// Cuenta normal
echo count($comida); // muestra 2

?>

Historial de cambios

Versión	Descripción
7.2.0	count() generará una advertencia si se pasan tipos contables no válido al parámetro `array_or_countable`.

Ver también

is_array() - Comprueba si una variable es un array
isset() - Determina si una variable está definida y no es null
empty() - Determina si una variable está vacía
strlen() - Obtiene la longitud de un string
is_countable() - Verifica que el contenido de una variable es un valor contable

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User Contributed Notes 13 notes

down

141

onlyranga at gmail dot com ¶

10 years ago

[Editor's note: array at from dot pl had pointed out that count() is a cheap operation; however, there's still the function call overhead.]



If you want to run through large arrays don't use count() function in the loops , its a over head in performance,  copy the count() value into a variable and use that value in loops for a better performance.



Eg:



// Bad approach



for($i=0;$i<count($some_arr);$i++)

{

    // calculations

}



// Good approach



$arr_length = count($some_arr);

for($i=0;$i<$arr_length;$i++)

{

    // calculations

}

down

lucasfsmartins at gmail dot com ¶

5 years ago

If you are on PHP 7.2+, you need to be aware of "Changelog" and use something like this:

<?php
$countFruits = is_array($countFruits) || $countFruits instanceof Countable ? count($countFruits) : 0;
?>

You can organize your code to ensure that the variable is an array, or you can extend the Countable so that you don't have to do this check.

down

Anonymous ¶

5 years ago

For a Non Countable Objects

$count = count($data);
print "Count: $count\n";

Warning:  count(): Parameter must be an array or an object that implements Countable in example.php on line 159

#Quick fix is to just cast the non-countable object as an array..  

$count = count((array) $data);
print "Count: $count\n";

Count: 250

down

danny at dannymendel dot com ¶

17 years ago

I actually find the following function more useful when it comes to multidimension arrays when you do not want all levels of the array tree.



// $limit is set to the number of recursions

<?php

function count_recursive ($array, $limit) {

    $count = 0;

    foreach ($array as $id => $_array) {

        if (is_array ($_array) && $limit > 0) {

            $count += count_recursive ($_array, $limit - 1);

        } else {

            $count += 1;

        }

    }

    return $count;

}

?>

down

pied-pierre ¶

9 years ago

A function of one line to find the number of elements that are not arrays, recursively :

function count_elt($array, &$count=0){
  foreach($array as $v) if(is_array($v)) count_elt($v,$count); else ++$count;
  return $count;
}

down

alexandr at vladykin dot pp dot ru ¶

18 years ago

My function returns the number of elements in array for multidimensional arrays subject to depth of array. (Almost COUNT_RECURSIVE, but you can point on which depth you want to plunge).



<?php

  function getArrCount ($arr, $depth=1) {

      if (!is_array($arr) || !$depth) return 0;

         

     $res=count($arr);

         

      foreach ($arr as $in_ar)

         $res+=getArrCount($in_ar, $depth-1);

      

      return $res;

  }

?>

down

olja dot fb at gmail dot com ¶

1 year ago

In example #3, given as:

<?php
$food = array('fruits' => array('orange', 'banana', 'apple'),
              'veggie' => array('carrot', 'collard', 'pea'));

// recursive count
var_dump(count($food, COUNT_RECURSIVE));
?>

with the output given as int(8), it may have some readers mistaken, as I was at first: one might take it as keys being counted as well as the inner array entries:

<?php
// NO:
'fruits', 'orange', 'banana', 'apple', 
'veggie', 'carrot', 'collard', 'pea'
?>

But actually keys are not counted in count function, and why it is still 8 - because inner arrays are counted as entries as well as their inner elements:

<?php
// YES:
array('orange', 'banana', 'apple'), 'orange', 'banana', 'apple', 
array('carrot', 'collard', 'pea'), 'carrot', 'collard', 'pea'
?>

down

-1

php_count at cubmd dot com ¶

7 years ago

All the previous recursive count solutions with $depth option would not avoid infinite loops in case the array contains itself more than once.

Here's a working solution:



<?php

    /**

     * Recursively count elements in an array. Behaves exactly the same as native

     * count() function with the $depth option. Meaning it will also add +1 to the

     * total count, for the parent element, and not only counting its children.

     * @param $arr

     * @param int $depth

     * @param int $i (internal)

     * @return int

     */

    public static function countRecursive(&$arr, $depth = 0, $i = 0) {

        $i++;

        /**

         * In case the depth is 0, use the native count function

         */

        if (empty($depth)) {

            return count($arr, COUNT_RECURSIVE);

        }

        $count = 0;

        /**

         * This can occur only the first time when the method is called and $arr is not an array

         */

        if (!is_array($arr)) {

            return count($arr);

        }



        // if this key is present, it means you already walked this array

        if (isset($arr['__been_here'])) {

            return 0;

        }



        $arr['__been_here'] = true;



        foreach ($arr as $key => &$value) {

            if ($key !== '__been_here') {

                if (is_array($value) && $depth > $i) {

                    $count += self::countRecursive($value, $depth, $i);

                }



                $count++;

            }

        }



        // you need to unset it when done because you're working with a reference...

        unset($arr['__been_here']);

        return $count;

    }

?>

down

-1

asma mechtaba ¶

2 years ago

count and sizeof are aliases, what work for one works for the other.

down

-2

Christoph097 ¶

2 years ago

Empty values are counted:
<?php
$ar[] = 3;
$ar[] = null;
var_dump(count($ar)); //int(2)
?>

down

-5

buyatv at gmail dot com ¶

7 years ago

You can not get collect sub array count when there is only one sub array in an array: 

$a = array ( array ('a','b','c','d'));
$b = array ( array ('a','b','c','d'), array ('e','f','g','h'));

echo count($a);  // 4 NOT 1, expect 1
echo count($b);  // 2,   expected

down

-5

vojtaripa at gmail dot com ¶

4 years ago

To get the count of the inner array you can do something like:

$inner_count = count($array[0]);
echo ($inner_count);

down

-4

max at schimmelmann dot org ¶

4 years ago

In special situations you might only want to count the first level of the array to figure out how many entries you have, when they have N more key-value-pairs.

<?php

$data = [
    'a' => [
        'bla1' => [
            0 => 'asdf',
            1 => 'asdf',
            2 => 'asdf',
        ],
        'bla2' => [
            0 => 'asdf',
            1 => 'asdf',
            2 => 'asdf',
        ],
        'bla3' => [
            0 => 'asdf',
            1 => 'asdf',
            2 => 'asdf',
        ],
        'bla4' => [
            0 => 'asdf',
            1 => 'asdf',
            2 => 'asdf',
        ],
    ],
    'b' => [
        'bla1' => [
            0 => 'asdf',
            1 => 'asdf',
            2 => 'asdf',
        ],
        'bla2' => [
            0 => 'asdf',
            1 => 'asdf',
            2 => 'asdf',
        ],
    ],
    'c' => [
        'bla1' => [
            0 => 'asdf',
            1 => 'asdf',
            2 => 'asdf',
        ]
    ]
];
$count = array_sum(array_values(array_map('count', $data)));
// will return int(7)
var_dump($count);

// will return 31
var_dump(count($data, 1));
?>

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