count

(PHP 4, PHP 5)

countCuenta todos los elementos de un array o en un objeto

Descripción

int count ( mixed $var [, int $mode = COUNT_NORMAL ] )

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

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

Por favor ver la sección del manual Array para una explicación más extensa de como se implementan y usan los arrays en PHP.

Parámetros

var

El array o el objecto

mode

Si el parámetro opcional mode está definido con la constante 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 lanzará 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 pueda esperar.

Valores devueltos

Devuelve el número de elementos en var, Si var no es un array o no es un objecto con la interfaz Countable implementada, devolverá 1. Existe una excepción, si var es NULL, devolverá 0.

Precaución

count() devolverá 0 si la variable que se intenta contar no está definida pero también devolverá 0 si la variable contiene un array vacío. Use isset() para comprobar si la variable está definida.

Historial de cambios

Versión Descripción
4.2.0 Se añadió el parámetro opcional mode.

Ejemplos

Ejemplo #1 Ejemplo de count()

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

$b[0]  = 7;
$b[5]  = 9;
$b[10] = 11;
$result count($b);
// $result == 3

$result count(null);
// $result == 0

$result count(false);
// $result == 1
?>

Ejemplo #2 Ejemplo de count() recursivo

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

// Count recursivo
echo count($foodCOUNT_RECURSIVE); // muestra 8

// Count normal
echo count($food); // muestra 2

?>

Ver también

  • is_array() - Comprueba si una variable es un array
  • isset() - Determina si una variable está definida y no es NULL
  • strlen() - Obtiene la longitud de un string

add a note add a note

User Contributed Notes 12 notes

up
24
alexandr at vladykin dot pp dot ru
7 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;
  }
?>
up
21
danny at dannymendel dot com
6 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;
}
?>
up
1
norbyte
1 month ago
If you want to check whether large arrays contain a specific (less) number of array elements, don't use count(). This is very slow because each element has to get iterated.

This is much faster:

function isArrayCount(array $array, $count) {
    $count = (int) $count;
    $result = reset($array);
    if ($count === 0) {
        // for empty arrays reset returns FALSE
        // we have to switch the boolean result
        $result = !$result;
    }
    for($i = 1; $i < $count; $i++) {
        if (next($array) === FALSE) {
            $result = FALSE;
            break;
        }
    }
    return $result;
}
up
-4
jezdec at email dot cz
5 years ago
Hi there,
there is a simple script with example for counting rows and columns of a two-dimensional array.

<?php
$data
= array(
   
"apples" =>
        array(
"red", "yellow", "pineapples"),
   
"bananas" =>
        array(
"small", "medium", "big"),
   
"vegs" =>
        array(
"potatoes", "carrots", "onions")
);

$rows = count($data,0);
$cols = (count($data,1)/count($data,0))-1;
print
"There are {$rows} rows and {$cols} columns in the table!";
?>
up
-2
MaxTheDragon at home dot nl
5 months ago
If you wish to test if an array contains any elements (or is empty), you might tempted to use count to do something like this:

<?php
if (count($my_array) > 0) {
// array is not empty...
}

// or this ...

if (count($my_array) === 0) {
// array is empty...
}
?>

Using the count function here is totally unnecessary and slower.

Instead, you should rely on the fact that empty arrays evaluate to false when cast to a boolean:

<?php
$hasElements
= (boolean) $my_array;

// or ...

$isEmpty = !$my_array;

// or in a conditional statement...

if ($my_array) {
// array is not empty...
}
?>

Only use count if you need to know if an array contains a specific number of elements n (where n > 0).
up
-5
atoi_monte at hotmail dot com
6 years ago
Please note: While SPL is compiled into PHP by default starting with PHP 5, the Countable interface is not available until 5.1
up
-5
semmelbroesel at gmail dot com
8 months ago
I've read this somewhere else before, but experienced it first hand now, so I thought I'd post it here.

While in regular use, count() is pretty fast, this changes rapidly when used in a for loop. Example:

for ($x = 0; $x < count($array); $x++)
{
  // some code here
}

If your array contains a lot of data, this code gets slowed down significantly. Better way to write this:

$arrayCount = count($array);
for ($x = 0; $x < $arrayCount; $x++)
{
  // some code here
}

I didn't think it would make such a difference, but it did in my case - changed 15 seconds load time into 1 second!
up
-1
Gerd Christian Kunze
4 months ago
Get maxWidth and maxHeight of a two dimensional array..?

Note:
1st dimension = Y (height)
2nd dimension = X (width)
e.g. rows and cols in database result arrays

<?php
$TwoDimensionalArray
= array( 0 => array( 'key' => 'value', ...), ... );
?>

So for Y (maxHeight)
<?php
$maxHeight
= count( $TwoDimensionalArray )
?>

And for X (maxWidth)
<?php
$maxWidth
= max( array_map( 'count'$TwoDimensionalArray ) );
?>

Simple? ;-)
up
-6
lopezvit at gmail dot com
6 months ago
I think that maybe that is faster (I don't know why, because, at least in C, for loops are faster than while ones due to compile optimization) but what is sure is that, in case the list is empty, you are going to iterate over the loop at least one. And I'm sure that is not what you want to do. The correct way in this occassion is to use a normal while, not a do, while.
up
-21
freefaler at gmail dot com
9 years ago
If you want to count only elements in the second level of 2D arrays.A close to mind note, useful for multidimentional arrays:

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

// recursive count
echo count($food,COUNT_RECURSIVE);  // output 8

// normal count
echo count($food);                  // output 2

// all the fruits and veggies
echo (count($food,COUNT_RECURSIVE)-count($food,0)); //output 6
?>
up
-27
nicolas dot grekas+php at gmail dot com
2 years ago
As of PHP 5.2.6, count() DOES detect infinite recursion.
It triggers a warning when its argument is a recursive array.
up
-27
me at me dot com
7 months ago
To the poster above, the fastest way is to use 'do/while'. Try this way, you will find it faster than 'for'.
$arrayCount = count($array);
do{
    // some code here
    --$arrayCount;
}
while($arrayCount > 0);
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