(PHP 4, PHP 5, PHP 7)
count — Count all elements in an array, or something in an object
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.
array_or_countableAn 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.
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.
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.
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($food); // output 2
?>
If you want to run through large arrays don't use count() function in the loops , its a over head in performance, copy the count() value into a variable and use that value in loops for a better performance.
Eg:
// Bad approach
for($i=0;$i<count($some_arr);$i++)
{
// calculations
}
// Good approach
$arr_length = count($some_arr);
for($i=0;$i<$arr_length;$i++)
{
// calculations
}
onlyranga at gmail dot com note about keeping count() in variable is not really correct, For some time now using variable and calling `count()` on each loop iteration costs you basically the same.
Proof: If you look into PHP sources then you see that for some time now it returns internal counter value instead of counting on each call. Here is `count` implementation: [1] where for array it calls `php_count_recursive` [2] which is then calls zend_hash_num_elements and returns `nNumOfElements` internal variable. It is not counting anything.
You may want to read this blog post about PHP internals too: https://nikic.github.io/2012/03/28/Understanding-PHPs-internal-array-implementation.html
[1] https://github.com/php/php-src/blob/PHP-5.5/ext/standard/array.c#L306
[2] https://github.com/php/php-src/blob/e10e151e9b92313a7085272c85bebf6c82017fce/ext/standard/array.c#L264
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[$i]);
?>
My function returns the number of elements in array for multidimensional arrays subject to depth of array. (Almost COUNT_RECURSIVE, but you can point on which depth you want to plunge).
<?php
function getArrCount ($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;
}
?>
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? ;-)
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 $count;
}
?>
A function of one line to find the number of elements that are not arrays, recursively :
function count_elt($array, &$count=0){
foreach($array as $v) if(is_array($v)) count_elt($v,$count); else ++$count;
return $count;
}
/** Count of objects */
class ABC{ }
$objecto = new ABC();
$total = count((array)$object); //Returns Zero.
$total = count($object); //Returns One
echo $total;
Please note: While SPL is compiled into PHP by default starting with PHP 5, the Countable interface is not available until 5.1
I've read this somewhere else before, but experienced it first hand now, so I thought I'd post it here.
While in regular use, count() is pretty fast, this changes rapidly when used in a for loop. Example:
for ($x = 0; $x < count($array); $x++)
{
// some code here
}
If your array contains a lot of data, this code gets slowed down significantly. Better way to write this:
$arrayCount = count($array);
for ($x = 0; $x < $arrayCount; $x++)
{
// some code here
}
I didn't think it would make such a difference, but it did in my case - changed 15 seconds load time into 1 second!
Hi there,
there is a simple script with example for counting rows and columns of a two-dimensional array.
<?php
$data = array(
"apples" =>
array("red", "yellow", "pineapples"),
"bananas" =>
array("small", "medium", "big"),
"vegs" =>
array("potatoes", "carrots", "onions")
);
$rows = count($data,0);
$cols = (count($data,1)/count($data,0))-1;
print "There are {$rows} rows and {$cols} columns in the table!";
?>
PHP - count an object returns 1?
This is how: $total = count((array)$objecto);
If you want to check whether large arrays contain a specific (less) number of array elements, don't use count(). This is very slow because each element has to get iterated.
This is much faster:
function isArrayCount(array $array, $count) {
$count = (int) $count;
$result = reset($array);
if ($count === 0) {
// for empty arrays reset returns FALSE
// we have to switch the boolean result
$result = !$result;
}
for($i = 1; $i < $count; $i++) {
if (next($array) === FALSE) {
$result = FALSE;
break;
}
}
return $result;
}
I think that maybe that is faster (I don't know why, because, at least in C, for loops are faster than while ones due to compile optimization) but what is sure is that, in case the list is empty, you are going to iterate over the loop at least one. And I'm sure that is not what you want to do. The correct way in this occassion is to use a normal while, not a do, while.
If you want to count only elements in the second level of 2D arrays.A close to mind note, useful for multidimentional arrays:
<?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($food); // output 2
// all the fruits and veggies
echo (count($food,COUNT_RECURSIVE)-count($food,0)); //output 6
?>
As of PHP 5.2.6, count() DOES detect infinite recursion.
It triggers a warning when its argument is a recursive array.
If you wish to test if an array contains any elements (or is empty), you might tempted to use count to do something like this:
<?php
if (count($my_array) > 0) {
// array is not empty...
}
// or this ...
if (count($my_array) === 0) {
// array is empty...
}
?>
Using the count function here is totally unnecessary and slower.
Instead, you should rely on the fact that empty arrays evaluate to false when cast to a boolean:
<?php
$hasElements = (boolean) $my_array;
// or ...
$isEmpty = !$my_array;
// or in a conditional statement...
if ($my_array) {
// array is not empty...
}
?>
Only use count if you need to know if an array contains a specific number of elements n (where n > 0).
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))
?>
I posted in my blog a small article talking about this function. If you want to visit it look at this url:
http://softontherocks.blogspot.com/2014/10/contar-los-elementos-de-un-array-en-php.html
To the poster above, the fastest way is to use 'do/while'. Try this way, you will find it faster than 'for'.
$arrayCount = count($array);
do{
// some code here
--$arrayCount;
}
while($arrayCount > 0);
