count
Подсчитывает количество элементов массива или что-то в объекте.
Для объектов, если у вас включена поддержка SPL, вы можете перехватить count() , реализуя интерфейс Countable. Этот интерфейс имеет ровно один метод, Countable::count() , который возвращает значение функции count() .
Пожалуйста, смотрите раздел "Массивы" в этом руководстве для более детального представления о реализации и использовании массивов в PHP.
Список параметров
Массив или Countable объект.
Если необязательный параметр mode установлен в COUNT_RECURSIVE (или 1), count() будет рекурсивно подсчитывать количество элементов массива. Это особенно полезно для подсчёта всех элементов многомерных массивов.
count() умеет определять рекурсию для избежания бесконечного цикла, но при каждом обнаружении выводит ошибку уровня E_WARNING (в случае, если массив содержит себя более одного раза) и возвращает большее количество, чем могло бы ожидаться.
Возвращаемые значения
Возвращает количество элементов в array_or_countable . Если параметр не является массивом или объектом, реализующим интерфейс Countable, будет возвращена 1. За одним исключением: если array_or_countable — NULL , то будет возвращён 0.
count() может возвратить 0 для переменных, которые не установлены, но также может возвратить 0 для переменных, которые инициализированы пустым массивом. Используйте функцию isset() для того, чтобы протестировать, установлена ли переменная.
Примеры
Пример #1 Пример использования 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
?>
Пример #2 Пример рекурсивного использования count()
<?php
$food = array( ‘fruits’ => array( ‘orange’ , ‘banana’ , ‘apple’ ),
‘veggie’ => array( ‘carrot’ , ‘collard’ , ‘pea’ ));
// рекурсивный count
echo count ( $food , COUNT_RECURSIVE ); // выводит 8
PHP Array Length Tutorial – How to Get an Array Size
Arrays are a powerful data type in PHP. And knowing how to quickly determine the size of an array is a useful skill.
In this article I’ll give you a quick overview of how arrays work, and then I’ll dive into how to get the size of PHP arrays.
If you already know what arrays are, you can jump straight ahead to the How to get an Array size? section.
What is an Array in PHP?
Before we dive into getting an array size, we need to make sure we understand what an array is. An array in PHP is a variable type that allows you to store more than one piece of data.
For example, if you were storing a simple string, you would use a PHP string type:
However, if you wanted to store a few more pieces of separate data, you might consider using a couple of string variables.
That’s all well and good, but what if you need to store more data, and quickly recall any of those items elsewhere in your code? That’s where an array comes in handy. You can still store the individual pieces of data but using a single variable.
Each item in that array can be referenced by its numeric key. So instead of needing to recall the single variables, you could reference a single array item by its numeric key.
In PHP, Array keys start at 0
For even more control, arrays also allow you to define your own array keys, using a string.
This allows you to also reference the array item by its string key.
You can also define arrays using the new short array notation, which is similar to JavaScript:
Arrays can also be nested, forming more complex array variables:
And, you can recall a specific array value using its nested key:
However, if you find yourself regularly doing this, you might want to consider using objects rather than arrays.
Arrays are useful if you need to quickly gather and then use different pieces of related data in a function, or pass that data to another function.
By putting these pieces of data into an array, you have fewer variables defined, and it can make your code easier to read and understand later on. It’s also a lot easier to pass a single array variable to another function than it is to pass multiple strings.
How to Get the Size of an Array in PHP
Usually when we talk about the size of an array, we’re talking about how many elements exist in that array. There are two common ways to get the size of an array.
The most popular way is to use the PHP count() function. As the function name says, count() will return a count of the elements of an array. But how we use the count() function depends on the array structure.
Let’s look at the two example arrays we defined earlier.
In this example, count($post_data) will result in 3. This is because there are 3 elements in that array: ‘heading’, ‘subheading’, and ‘author’. But what about our second, nested array example?
Believe it or not, in this example, count($post_data) will also return 3. This is because by default the count() function only counts the top level array elements.
If you take a look at the function definition, you will see that it accepts two arguments – the array to be counted, and a mode integer. The default value for that mode is the predefined constant COUNT_NORMAL , which tells the function to only count the top level array elements.
If we pass the predefined constant COUNT_RECURSIVE instead, it will run through all levels of nesting, and count those instead.
Now, the result of count($post_data, COUNT_RECURSIVE) will be, as expected, 5.
«But wait!», I hear you cry. «you mentioned there was another way?».
Well yes, the other function you can use is sizeof(). However, sizeof() is just an alias of count() , and many folks assume (rightly so) that sizeof() would return the memory usage of an array.
Therefore it’s better to stick with count() , which is a much more suitable name for what you are doing – counting elements in an array.
Thanks for reading! I hope you now have a better understanding of how to find the size of an array in PHP.
count
Подсчитывает все элементы в массиве, если используется массив. Если используется объект, который реализует интерфейс Countable , функция возвращает результат выполнения метода Countable::count() .
Список параметров
Массив или объект, реализующий Countable .
Если необязательный параметр mode установлен в COUNT_RECURSIVE (или 1), count() будет рекурсивно подсчитывать количество элементов массива. Это особенно полезно для подсчёта всех элементов многомерных массивов.
count() умеет определять рекурсию для избежания бесконечного цикла, но при каждом обнаружении выводит ошибку уровня E_WARNING (в случае, если массив содержит себя более одного раза) и возвращает большее количество, чем могло бы ожидаться.
Возвращаемые значения
Возвращает количество элементов в value . До PHP 8.0.0, если параметр не был ни массивом ( array ), ни объектом ( object ), реализующим интерфейс Countable , возвращалось 1 , если значение параметра value не было null , в этом случае возвращалось 0 .
Список изменений
| Версия | Описание |
|---|---|
| 8.0.0 | count() теперь выбрасывает TypeError , если передан недопустимый исчисляемый тип в параметр value . |
| 7.2.0 | count() теперь будет выдавать предупреждение о недопустимых исчисляемых типах, переданных в параметр value . |
Примеры
Пример #1 Пример использования count()
<?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 ));
?>
Результат выполнения данного примера:
Пример #2 Пример использования count() с неисчисляемым типом (плохой пример — не делайте так)
<?php
$b [ 0 ] = 7 ;
$b [ 5 ] = 9 ;
$b [ 10 ] = 11 ;
var_dump ( count ( $b ));
var_dump ( count ( null ));
var_dump ( count ( false ));
?>
Результат выполнения данного примера:
Результат выполнения данного примера в PHP 7.2:
Результат выполнения данного примера в PHP 8:
Пример #3 Пример рекурсивного использования count()
<?php
$food = array( ‘fruits’ => array( ‘orange’ , ‘banana’ , ‘apple’ ),
‘veggie’ => array( ‘carrot’ , ‘collard’ , ‘pea’ ));
// рекурсивный подсчёт
var_dump ( count ( $food , COUNT_RECURSIVE ));
// обычный подсчёт
var_dump ( count ( $food ));
Результат выполнения данного примера:
Пример #4 Объект, реализующий интерфейс Countable
<?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 ));
?>
Результат выполнения данного примера:
Смотрите также
- is_array() — Определяет, является ли переменная массивом
- isset() — Определяет, была ли установлена переменная значением, отличным от null
- empty() — Проверяет, пуста ли переменная
- strlen() — Возвращает длину строки
- is_countable() — Проверить, что содержимое переменной является счётным значением
User Contributed Notes 18 notes
[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.
$arr_length = count($some_arr);
for($i=0;$i<$arr_length;$i++)
<
// calculations
>
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.
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»;
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 ;
>
?>
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’
?>
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 , $depth — 1 );
A function of one line to find the number of elements that are not arrays, recursively :
function count_elt($array, &$count=0) <
foreach($array as $v) if(is_array($v)) count_elt($v,$count); else ++$count;
return $count;
>
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 );
>
// you need to unset it when done because you’re working with a reference.
unset( $arr [ ‘__been_here’ ]);
return $count ;
>
?>
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? 😉
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
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 [ $i ]);
?>
You can not get collect sub array count when use the key on only one sub array in an array:
echo count($a[‘b’]); // 2 NOT 1, expect 1
echo count($b[‘b’]); // 3, expected
To get the count of the inner array you can do something like:
$inner_count = count($array[0]);
echo ($inner_count);
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))
?>
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.
// will return 31
var_dump ( count ( $data , 1 ));
?>
If you want to know the sub-array containing the MAX NUMBER of values in a 3 dimensions array, here is a try (maybe not the nicest way, but it works):
function how_big_is_the_biggest_sub ($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
Array Length PHP Calculate PHP Array Length
How to calculate the PHP array length?
If you want to count the total number of elements or values in an array, you can easily do it by using PHP inbuilt functions called count() or sizeof().
You can find a detailed explanation with the example below that how you can calculate PHP array length.
count(): PHP Array Length For Loop
The Syntax for PHP count() function is very simple.
array_or_countable
The first argument is an array variable that is required to calculate the PHP array length. If the first argument is empty, an empty array or not set, then count() function will return 0.
And, If the variable is specified but its data type is not an array, then, count() function will return 1.
To avoid this, you can use the PHP inbuilt function isset() and check whether an array variable is set or not.
The second argument is optional and can take two values either COUNT_NORMAL or COUNT_RECURSIVE. You can pass the value 0 and 1 instead of COUNT_NORMAL and COUNT_RECURSIVE that will make the same effect.
The default value of the second argument is COUNT_NORMAL if no value passed as the second argument.
Example #1 count() example
In the above code block, We have created a multidimensional array.
When we use count function in the RECURSIVE mode as a second argument, Output is 8.
And, when we use count function in the NORMAL mode as a second argument or default mode, Output is 2.
sizeof()— PHP Array Length?
sizeof() is an alias of PHP count() function and accepts the same arguments as count().
If We replace the count() with sizeof() in the above example, the results of both functions will be the same for both functions calls.
Many programmers who come from C language background expect sizeof() to return the amount of memory allocated. But, sizeof() — as described above — is an alias for count() in PHP.
It is advised to always use count() instead of sizeof(). Because there is no guarantee for the alias function if they will exist or not in a future upgrade.
So, you should always consider to maintain code standard as well as avoid to break the application due to the upgraded version.