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count
(PHP 4, PHP 5, PHP 7, PHP 8) count — Counts all elements in an array or in a Countable object
Description
Counts all elements in an array when used with an array. When used with an
object that implements the Countable interface, it returns
the return value of the method Countable::count().
Parameters
value-
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 value.
Prior to PHP 8.0.0, if the parameter was neither an array nor an object that
implements the Countable interface,
1 would be returned,
unless value was null, in which case
0 would be returned.
Changelog
| Version |
Description |
| 8.0.0 |
Now throws a ValueError if
mode is not COUNT_NORMAL or
COUNT_RECURSIVE.
|
| 8.0.0 |
count() will now throw TypeError on
invalid countable types passed to the value parameter.
|
| 7.2.0 |
count() will now yield a warning on invalid countable types
passed to the value parameter.
|
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));
?>
The above example will output:
Example #2 count() non Countable|array example (bad example - don't do this)
<?php
$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)
Fatal error: Uncaught TypeError: count(): Argument #1 ($var) must be of type Countable .. on line 12
Example #3 Recursive count() example
<?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($food));
?>
The above example will output:
Example #4 Countable object
<?php
class CountOfMethods implements Countable
{
private function someMethod()
{
}
public function count(): int
{
return count(get_class_methods($this));
}
}
$obj = new CountOfMethods();
var_dump(count($obj));
?>
The above example will output:
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
- Arrays
onlyranga at gmail dot com ¶12 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
}
lucasfsmartins at gmail dot com ¶7 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.
danny at dannymendel dot com ¶19 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 $count;
}
?>
alexandr at vladykin dot pp dot ru ¶20 years ago
My function returns the number of elements in array for multidimensional arrays subject to depth of array. (Almost COUNT_RECURSIVE, but you can point on which depth you want to plunge).
<?php
function getArrCount ($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;
}
?>
Anonymous ¶7 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: $count\n";
Count: 250
pied-pierre ¶11 years ago
A function of one line to find the number of elements that are not arrays, recursively :
function count_elt($array, &$count=0){
foreach($array as $v) if(is_array($v)) count_elt($v,$count); else ++$count;
return $count;
}
|