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    count

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

    count — 配列または Countable オブジェクトに含まれるすべての要素の数を数える

    説明

    count(Countable|array $value, int $mode = COUNT_NORMAL): int

    配列の場合は、配列の全ての要素を数えます。 Countable インターフェイスを実装したオブジェクトの場合は、 Countable::count() の戻り値を返します。

    パラメータ

    value

    配列あるいは Countable オブジェクト。

    mode

    オプションのmode 引数が COUNT_RECURSIVE (または 1) にセットされた場合、count() は再帰的に配列をカウントします。 これは多次元配列の全ての要素をカウントするといった場合に特に有効です。

    警告

    count() は、再帰を検出して無限ループを回避するようになっています。 しかしその場合 (配列の中に自分自身が複数回登場する場合) は毎回 E_WARNING を発行し、期待する結果より大きい数を返します。

    戻り値

    value の要素の数を返します。 PHP 8.0.0 より前のバージョンでは、 パラメータが配列でもなく Countable インターフェイスを 実装したオブジェクトでもない場合、1 が返されていました。 ただし、value が null の場合、 0 が返されていました。

    変更履歴

    バージョン 説明
    8.0.0 value パラメータに不正な型を渡した場合に、 TypeError をスローするようになりました。
    7.2.0 value パラメータに不正な型を渡した場合に、 警告を発生させるようになりました。

    例

    例1 count() の例

    <?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));
    ?>

    上の例の出力は以下となります。

    int(3)
int(3)

    例2 Countable|array でない値を渡した場合の count() の例 (悪い例です - 真似しないでね！)

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

    var_dump(count(null));

    var_dump(count(false));
    ?>

    上の例の出力は以下となります。

    int(3)
int(0)
int(1)

    上の例の PHP 7.2 での出力は、このようになります。

    int(3)

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

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

    上の例の PHP 8 での出力は、このようになります。:

    int(3)

Fatal error: Uncaught TypeError: count(): Argument #1 ($var) must be of type Countable .. on line 12

    例3 再帰的な count() の例

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

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

    // normal count
    var_dump(count($food));

    ?>

    上の例の出力は以下となります。

    int(8)
int(2)

    例4 Countable オブジェクトの例

    <?php
    class CountOfMethods implements Countable
    {
    private function     someMethod()
    {
    }

    public function     count(): int
    {
    return     count(get_class_methods($this));
    }
    }

    $obj = new CountOfMethods();
    var_dump(count($obj));
    ?>

    上の例の出力は以下となります。

    int(2)

    参考

    • is_array() - 変数が配列かどうかを検査する
    • isset() - 変数が宣言されていること、そして null とは異なることを検査する
    • empty() - 変数が空であるかどうかを検査する
    • strlen() - 文字列の長さを得る
    • is_countable() - 引数が、数えられる値かどうかを調べる
    • Arrays

    add a note add a note

    User Contributed Notes 18 notes

    up
    137
    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
    }
    up
    6
    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
    up
    4
    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.
    up
    1
    Christoph097
    2 years ago
    Empty values are counted:
    <?php
    $ar    [] = 3;
    $ar[] = null;
    var_dump(count($ar)); //int(2)
    ?>
    up
    12
    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;
    }
    ?>
    up
    0
    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'
    ?>
    up
    0
    asma mechtaba
    2 years ago
    count and sizeof are aliases, what work for one works for the other.
    up
    9
    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;
      }
    ?>
    up
    1
    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;
    }
    up
    0
    php_count at cubmd dot com
    8 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
    -3
    Gerd Christian Kunze
    11 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
    -6
    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
    up
    -9
    JumpIfBelow
    9 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
    -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);
    up
    -18
    buyatv at gmail dot com
    7 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
    -30
    ThisIsNotImportant
    9 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
    -6
    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));
    ?>
    up
    -10
    XavDeb
    4 years ago
    If you want to know the sub-array containing the MAX NUMBER of values in a 3 dimensions array, here is a try (maybe not the nicest way, but it works):

    function how_big_is_the_biggest_sub ($array)  {
       // we parse the 1st level
       foreach ($array AS $key => $array_lvl2) {
             //within level 2, we count the 3d levels max
                $lvl2_nb = array_map( 'count',  $array_lvl2) ;
                $max_nb = max($lvl2_nb);
             // we store the matching keys, it might be usefull
                $max_key = array_search($max_nb, $lvl2_nb);
                $max_nb_all[$max_key.'|'.$key] = $max_nb;
            }
           // now we want the max from all levels 2, so one more time
            $real_max = max($max_nb_all);
            $real_max_key = array_search($real_max, $max_nb_all);
            list($real_max_key2, $real_max_key1) = explode('|', $real_max_key);
                    // preparing result
            $biggest_sub['max'] = $real_max;
            $biggest_sub['key1'] = $real_max_key1;
            $biggest_sub['key2'] = $real_max_key2;
           
            return $biggest_sub;
    }
    /*
    $cat_poids_max['M']['Juniors'][] = 55;
    $cat_poids_max['M']['Juniors'][] = 61;
    $cat_poids_max['M']['Juniors'][] = 68;
    $cat_poids_max['M']['Juniors'][] = 76;
    $cat_poids_max['M']['Juniors'][] = 100;

    $cat_poids_max['M']['Seniors'][] = 55;
    $cat_poids_max['M']['Seniors'][] = 60;
    $cat_poids_max['M']['Seniors'][] = 67;
    $cat_poids_max['M']['Seniors'][] = 75;
    $cat_poids_max['M']['Seniors'][] = 84;
    $cat_poids_max['M']['Seniors'][] = 90;
    $cat_poids_max['M']['Seniors'][] = 100;
    //....
    $cat_poids_max['F']['Juniors'][] = 52;
    $cat_poids_max['F']['Juniors'][] = 65;
    $cat_poids_max['F']['Juniors'][] = 74;
    $cat_poids_max['F']['Juniors'][] = 100;

    $cat_poids_max['F']['Seniors'][] = 62;
    $cat_poids_max['F']['Seniors'][] = 67;
    $cat_poids_max['F']['Seniors'][] = 78;
    $cat_poids_max['F']['Seniors'][] = 86;
    $cat_poids_max['F']['Seniors'][] = 100;
    */
    $biggest_sub = how_big_is_the_biggest_sub($cat_poids_max);
    echo "<li> ".$biggest_sub['key1']." ==> ".$biggest_sub['key2']." ==> ".$biggest_sub['max']; // displays : M ==> Seniors ==> 7
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