count
(PHP 4, PHP 5)
count — Count all elements in an array, or something in an object
Description
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
modeparameter is set toCOUNT_RECURSIVE(or 1), count() will recursively count the array. This is particularly useful for counting all the elements of a multidimensional array.Cautioncount() can detect recursion to avoid an infinite loop, but will emit an
E_WARNINGevery 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.
If the parameter is not an array or not an object with
implemented Countable interface,
1 will be returned.
There is one exception, if array_or_countable is NULL,
0 will be returned.
count() may return 0 for a variable that isn't set, but it may also return 0 for a variable that has been initialized with an empty array. Use isset() to test if a variable is set.
Changelog
| Version | Description |
|---|---|
| 4.2.0 |
The optional mode parameter was added.
|
Examples
Example #1 count() example
<?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
?>
Example #2 Recursive count() example
<?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($food); // output 2
?>
See Also
- is_array() - Finds whether a variable is an array
- isset() - Determine if a variable is set and is not NULL
- strlen() - Get string length
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Коментарии
My function returns the number of elements in array for multidimensional arrays subject to depth of array. (Almost COUNT_RECURSIVE, but you can point on which depth you want to plunge).
<?php
function getArrCount ($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;
}
?>
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 $count;
}
?>
[Editor's note: array at from dot pl had pointed out that count() is a cheap operation; however, there's still the function call overhead.]
If you want to run through large arrays don't use count() function in the loops , its a over head in performance, copy the count() value into a variable and use that value in loops for a better performance.
Eg:
// Bad approach
for($i=0;$i<count($some_arr);$i++)
{
// calculations
}
// Good approach
$arr_length = count($some_arr);
for($i=0;$i<$arr_length;$i++)
{
// calculations
}
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;
}
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";
Count: 250