PHP 5.4.31 Released

count

(PHP 4, PHP 5)

countZlicza ilość elementów w tablicy lub pól obiektu

Opis

int count ( mixed $zmienna [, int $tryb ] )

Zwraca ilość elementów w parametrze zmienna, która zazwyczaj będzie tablicą, jako że wszystko inne będzie miało jeden element.

Dla obiektów, jeśli zainstalowane zostało rozszerzenie SPL, możliwe jest podłączenie do count() poprzez zaimplementowanie interfejsu Countable. Interfejs ten posiada dokładnie jedną metodę, count(), która zwraca wartość, którą ma zwrócić funkcja count().

Jeśli zmienna nie jest tablicą ani obiektem z zaimplementowanym interfejsem Countable, to zwracana będzie wartość 1. Istnieje jeden wyjątek - jeśli zmienna będzie miała wartość NULL, zwrócona zostanie wartość 0.

Informacja: Opcjonalny argument tryb dostępny jest od wersji PHP 4.2.0.

Jeśli opcjonalny argument tryb ustawiony jest na COUNT_RECURSIVE (lub 1), count() będzie zliczał elementy rekurencyjnie. Jest to przydatne przy zliczaniu ilości wszystkich elementów tablicy wielowymiarowej. Domyślna wartość argumentu tryb to 0. count() nie wykrywa nieskończonej rekurencji.

Uwaga

count() może zwrócić 0 dla zmiennej, która nie została zainicjalizowana, ale możę zwrócić także 0 dla zmiennej która została zainicjalizowana pustą tablicą. Użyj isset() aby sprawdzić czy zmienna została ustawiona.

Więcej informacji na temat sposobu implementacji tablic w PHP można znaleźć w rozdziale Tablice.

Przykład #1 Przykład użycia count()

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

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

$wynik count(null);
// $wynik == 0

$wynik count(false);
// $wynik = 1

?>

Przykład #2 Przykład rekurencyjnego przetwarzania przez count() (PHP >= 4.2.0)

<?php
$jedzenie 
= array('owoce' => array('pomarańcza''banan''jabłko'),
                
'warzywa' => array('marchewka''kukurydza''groszek'));

// zliczanie rekurencyjne
echo count($jedzenieCOUNT_RECURSIVE); // wyświetli 8

// normal count
echo count($jedzenie); // wyświetli 2

?>

Patrz także: is_array(), isset() i strlen().

add a note add a note

User Contributed Notes 13 notes

up
35
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
17
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
0
onlyranga at gmail dot com
2 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
0
norbyte
4 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
0
Gerd Christian Kunze
7 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
-5
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
-6
semmelbroesel at gmail dot com
11 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
-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
-5
lopezvit at gmail dot com
9 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
MaxTheDragon at home dot nl
8 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
-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
-28
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
-28
me at me dot com
10 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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