count

(PHP 4, PHP 5)

countCompte tous les éléments d'un tableau ou quelque chose d'un objet

Description

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

Compte tous les éléments d'un tableau ou quelque chose d'un objet.

Pour les objets, count() retourne le nombre de propriétés non-statiques, sans tenir compte de la visibilité. Si SPL est disponible, vous pouvez utiliser la fonction count() en implémentant l'interface Countable. Cette interface a exactement une méthode, Countable::count(), qui retourne la valeur retournée par la fonction count().

Reportez-vous à la section sur les Tableaux du manuel, pour plus de détails sur le fonctionnement des tableaux en PHP.

Liste de paramètres

array_or_countable

Un tableau ou un objet Countable.

mode

Si le paramètre optionnel mode vaut COUNT_RECURSIVE (ou 1), count() va compter récursivement les tableaux. C'est particulièrement pratique pour compter le nombre d'éléments d'un tableau.

Attention

La fonction count() peut détecter les récursions afin d'éviter les boucles infinies, mais émettra une alerte de type E_WARNING à chaque fois qu'une boucle infinie surviendra (dans le cas où un tableau contient lui-même plus d'une boucle infinie) et retournera un compteur plus grand que l'attendu.

Valeurs de retour

Retourne le nombre d'éléments dans array_or_countable. Si le paramètre n'est ni un objet, ni un tableau, 1 sera retourné. Il y a néanmoins une exception : si le paramètre array_or_countable vaut NULL, 0 sera retourné.

Attention

count() peut retourner 0 pour une variable qui n'a pas été affectée, ou pour un tableau vide. Utilisez plutôt isset() pour tester si la variable existe.

Historique

Version Description
4.2.0 Le paramètre optionnel mode a été ajouté.

Exemples

Exemple #1 Exemple avec 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
?>

Exemple #2 Exemple de récursivité avec count()

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

// count récursif
echo count($foodCOUNT_RECURSIVE); // affiche 8

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

?>

Voir aussi

  • is_array() - Détermine si une variable est un tableau
  • isset() - Détermine si une variable est définie et est différente de NULL
  • strlen() - Calcule la taille d'une chaîne

add a note add a note

User Contributed Notes 13 notes

up
28
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
14
danny at dannymendel dot com
7 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
Gerd Christian Kunze
8 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
0
onlyranga at gmail dot com
3 months ago
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
}
up
-4
atoi_monte at hotmail dot com
7 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
-3
MaxTheDragon at home dot nl
9 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
-7
semmelbroesel at gmail dot com
1 year 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
-9
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
-7
lopezvit at gmail dot com
10 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
-4
norbyte
5 months 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
-23
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
-26
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
-31
me at me dot com
11 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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