parent root
PHP: count - Manual
PHP 7.2.23 Release Announcement

count

(PHP 4, PHP 5, PHP 7)

countCount all elements in an array, or something in an object

Description

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

Counts all elements in an array, or something in an object.

For objects, if you have SPL installed, you can hook into count() by implementing interface Countable. The interface has exactly one method, Countable::count(), which returns the return value for the count() function.

Please see the Array section of the manual for a detailed explanation of how arrays are implemented and used in PHP.

Parameters

array_or_countable

An array or Countable object.

mode

If the optional mode parameter is set to COUNT_RECURSIVE (or 1), count() will recursively count the array. This is particularly useful for counting all the elements of a multidimensional array.

Caution

count() can detect recursion to avoid an infinite loop, but will emit an E_WARNING every time it does (in case the array contains itself more than once) and return a count higher than may be expected.

Return Values

Returns the number of elements in array_or_countable. When the parameter is neither an array nor an object with implemented Countable interface, 1 will be returned. There is one exception, if array_or_countable is NULL, 0 will be returned.

Examples

Example #1 count() example

<?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));
?>

The above example will output:

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)

Example #2 Recursive count() example

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

// recursive count
echo count($foodCOUNT_RECURSIVE); // output 8

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

?>

Changelog

Version Description
7.2.0 count() will now yield a warning on invalid countable types passed to the array_or_countable parameter.

See Also

  • is_array() - Finds whether a variable is an array
  • isset() - Determine if a variable is declared and is different than NULL
  • empty() - Determine whether a variable is empty
  • strlen() - Get string length
  • is_countable() - Verify that the contents of a variable is a countable value
add a noteadd a note

User Contributed Notes 13 notes

up
108
onlyranga at gmail dot com
5 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
}
up
5
lucasfsmartins at gmail dot com
6 months 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.
up
22
alexandr at vladykin dot pp dot ru
12 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
7
buyatv at gmail dot com
2 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
up
14
danny at dannymendel dot com
12 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
4
php_count at cubmd dot com
2 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;
    }
?>
up
4
pied-pierre
4 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;
}
up
5
Gerd Christian Kunze
5 years 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
1
jerome dot gds at gmail dot com
10 days ago
to end the debate: count() is the same as empty()

test code below:

results on my computer:

count : double(0.81396999359131)
empty : double(0.81621310710907)

using isset($test[0]) is a bit slower than empty;
test without adding value to the array in function ****Test: still the same.

<?php

function average(array $test)
{
   
$sum = 0;
    foreach(
$test as $value) {
       
$sum += $value;
    }

    return
$sum;
}

function
countTest(array $test)
{
   
$i = 0;
    while (
$i++ < 1000000) {
       
count($test);
       
$test["lol$i"] = "teset$i";
    }
}

function
emptyTest(array $test)
{
   
$i = 0;
    while (
$i++ < 1000000) {
        empty(
$test);
       
$test["lol$i"] = "teset$i";
    }
}

$test = [];
$i = 0;
while (
$i++ < 20000000) {
   
$test[] = $i;
}

$j = 10;
$value = $j;
$count = [];
$isEmpty = [];
while (
$j--) {
   
$time = microtime(true);
   
countTest($test);
   
$count[] = microtime(true) - $time;

   
$time = microtime(true);
   
emptyTest($test);
   
$isEmpty[] = microtime(true) - $time;
}

var_dump(average($count) / $value);
var_dump(average($isEmpty) / $value);
up
-1
JumpIfBelow
4 years ago
As I see in many codes, don't use count to iterate through array.
Onlyranga says you could declare a variable to store it before the for loop.
I agree with his/her approach, using count in the test should be used ONLY if you have to count the size of the array for each loop.

You can do it in the for loop too, so you don't have to "search" where the variable is set.
e.g.
<?php
    $array
= [1, 5, 'element'];
    for(
$i = 0, $c = count($array); $i < $c; $i++)
       
var_dump($array[$i]);
?>
up
-9
buyatv at gmail dot com
2 years ago
You can not get collect sub array count when use the key on only one sub array in an array:

$a = array("a"=>"appple", b"=>array('a'=>array(1,2,3),'b'=>array(1,2,3)));
$b = array("a"=>"appple", "b"=>array(array('a'=>array(1,2,3),'b'=>array(1,2,3)), array(1,2,3),'b'=>array(1,2,3)), array('a'=>array(1,2,3),'b'=>array(1,2,3))));

echo count($a['b']);  // 2 NOT 1, expect 1
echo count($b['b']);  // 3,   expected
up
-17
ThisIsNotImportant
3 years ago
About 2d arrays, you have many way to count elements :

<?php
$MyArray
= array ( array(1,2,3),
                  
1,
                  
'a',
                   array(
'a','b','c','d') );

// All elements
echo count($MyArray ,COUNT_RECURSIVE);  // output 11 (9 values + 2 arrays)

// First level elements
echo count($MyArray );                  // output 4 (2 values+ 2 arrays)

// Both level values, but only values
echo(array_sum(array_map('count',$MyArray ))); //output 9 (9 values)

// Only second level values
echo (count($MyArray ,COUNT_RECURSIVE)-count($MyArray )); //output 7 ((all elements) - (first elements))
?>
up
-3
flavioaugusto dot br at gmail dot com
7 months ago
Criada para contar quantos níveis um array multidimensional possui.

function count_multiLevel($matrix, $_LEVEL = 0){
       
        /* Variáveis de recursão */
        $_COUNT = $_LEVEL;
       
        /* Verifica se o ARRAY foi instanciado */
        if (is_setVar($matrix)){
           
            /* Verifica se a variável é um ARRAY */
            if(is_array($matrix)){
               
                /* Loop de elementos da matriz*/
                foreach ($matrix as $elements => $value) {
                   
                    /* Auxiliar para verificação posterior */
                    $_AUX = $_COUNT;
                   
                    /* Verifiando os Nós */
                    if (is_array($matrix[$elements])) {
                        $_COUNT = count_multiLevel($matrix[$elements], $_LEVEL+1);   
                    }
                    /* Cereja do bolo */
                    if($_AUX > $_COUNT)
                        $_COUNT = $_AUX;
                }
                /* Retorn do resultado da operação */
                return $_COUNT;
               
            }else{
                /* Em casos que o valor passado não seja uma matriz/array */
                return -1;
            }
        }
    }
To Top
parent root