Here is an iterative soloution of danny's count_recursive function which might be more efficient due to the missing recursion
<?php
/**
* counts elements of an multidimensional array
*
* @param array $array Input Array
* @param int $limit dimensions that shall be considered (-1 means no limit )
* @return int counted elements
*/
function multicount ($array, $limit = -1)
{
$cnt = 0;
$limit = $limit > 0 ? (int) $limit : -1;
$arrs[] = $array;
for ($i=0; isset($arrs[$i]) && is_array($arrs[$i]); ++$i)
{
foreach ($arrs[$i] as $value)
{
if (!is_array($value) ) ++$cnt;
elseif( $limit==-1 || $limit>1 )
{
if( $limit>1 ) --$limit;
$arrs[] = $value;
}
}
}
return $cnt;
}
?>
count
(PHP 4, PHP 5)
count — 変数に含まれる要素、 あるいはオブジェクトに含まれるプロパティの数を数える
説明
int count
( mixed $var
[, int $mode
] )
var に含まれる要素の数を返します。 他のものには、1つの要素しかありませんので、通常 var は配列です。
オブジェクトに対して、もし SPL がインストールされている場合、インターフェース Countable を実装することで count() にフックすることができます。このインターフェースには 1 つのメソッド count() があり、count() 関数に対する値を返します。
もし var が配列もしくは Countable インターフェースを実装したオブジェクトではない場合、 1 が返されます。 ひとつ例外があり、var が NULL の場合、 0 が返されます。
注意: オプションの引数 mode は PHP 4.2.0 以降で使用可能です。
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。 mode のデフォルトは 0 です。 count() は無限の再帰を検出しません。
警告
count() は、セットされていない変数に関して 0 を返しますが、変数が空の配列として初期化されている場合にも 0 を返します。 ある変数がセットされているかどうかを調べるには、 isset() を使用してください。
配列の実装やPHPでの使用法に関する詳細な説明については、マニュアルの 配列のセクションを参照ください。
Example#1 count() の例
<?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 再帰的な count() の例 (PHP >= 4.2.0)
<?php
$food = array('fruits' => array('orange', 'banana', 'apple'),
'veggie' => array('carrot', 'collard', 'pea'));
// 再帰的なカウント
echo count($food, COUNT_RECURSIVE); // output 8
// 通常のカウント
echo count($food); // output 2
?>
is_array()、 isset() および strlen() も参照ください。
count
Anonymous
11-Jan-2008 06:20
11-Jan-2008 06:20
Anonymous
17-Nov-2007 01:31
17-Nov-2007 01:31
I can confirm Wulfson's comment below. The for loop should be faster in most situations, just as long as you're iterating through a sequentially indexed array.
In fact, from my experience using foreach to iterate through an associative array is actually slower than using a while loop.
<?php
/* foreach iterator */
foreach($assoc_array as $key => $value) { }
/* while iterator */
while(list($key, $value) = each($assoc_array)) { }
?>
Wulfson at wulfden dot com
03-Nov-2007 06:08
03-Nov-2007 06:08
The last two comments (redbehelit and Jaik) are a little misguided. In a 26 element array,
for ($i = 0; $i < count($arr); $i++) {
works just fine, as count($arr) will return 26, which means that the loop will end as soon as $i gets iterated to 26 (26 < 26 is false). You'd only have to use count($arr) - 1 if your conditional was $i <=
Jaik is correct that it's better not to use count() inside the loop construct. As mentioned in a previous comment, it'd be faster to use
$size = count($arr);
for ($i = 0; $i < $size; $i++) {
I don't agree that foreach should be used instead of this, however. In my trials, I found that using a normal for loop was consistently faster than using a foreach (granted, not a whole lot faster, but everything counts if you're trying to optimize). foreach really ought to only be used when the array you're traversing contains associative indices.
Jaik
25-Oct-2007 10:51
25-Oct-2007 10:51
The last comment is somewhat inefficient as it runs the count() function at the start of every loop.
The preferred way to iterate through an array would be to use the 'foreach' control structure.
redbehelit at yahoo dot com
17-Oct-2007 04:24
17-Oct-2007 04:24
Be careful if you're using count in a loop. Example:
$arr ends at index number 25 (or $arr[25])
We know there are actually 26 elements when we include element 0 (as we should). This is what count is going to return back. But if we do this:
for ($i = 0; $i < count($arr); i++) {
This loop is going to try to traverse to $arr[26] which does not exist. The last element is at index number 25. We can fix this with a minor edit:
for ($i = 0; $i < count($arr)-1; i++) {
atoi_monte at hotmail dot com
29-Jun-2007 06:10
29-Jun-2007 06:10
Please note: While SPL is compiled into PHP by default starting with PHP 5, the Countable interface is not available until 5.1
danny at dannymendel dot com
14-Jun-2007 05:14
14-Jun-2007 05:14
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, $limit)
{
foreach ($array as $id => $_array)
{
if (is_array ($_array) && $limit > 0) $count += count_recursive ($_array, $limit - 1); else $count += 1;
}
return $count;
}
?>
yarolan at mail dot ru
26-Apr-2007 08:56
26-Apr-2007 08:56
NEVER USE IN CYCLES!
//size of $arr ~ 2000 elements
//wrong variant (Time exec ~ 19 sec)
for($i=0;$i<count($arr);$i++)
{
...
}
//right variant(Time exec ~ 0.2 sec)
$arr_size=count($arr);
for($i=0;$i<$arr_size;$i++)
{
...
}
it was discovered experimentally.
Colin
04-Feb-2007 12:24
04-Feb-2007 12:24
// countValuesRecursive
// The goal of this function is to count non-false values of a multidimenional array
// This is useful in making a quick determination if a form sent any values
// If no values were sent I can simply return to the blank form rather than continuing to the validation of each input
// There are two limitations of the principle:
// 1. If you WANT to send FALSE, 0, '', or NULL as form values this function will not count those, thus not doing what's expected
// 2. This would create an endless loop on a form that has no required fields such as one where users can choose to recieve optional email subscriptions but where choosing none is also valid
function countValuesRecursive($array, $count = 0) {
// Cycle through the array
foreach ($array as $value) {
// Check if the value is an array
if (is_array($value)) {
// Cycle through deeper level
$count = countValuesRecursive($value, $count);
}
else {
// Check if the value is TRUE
if ($value) {
$count++;
}
}
}
// Return the count
return $count;
}
alexandr at vladykin dot pp dot ru
08-Nov-2006 09:28
08-Nov-2006 09:28
My function returns the number of elements in array for multidimensional arrays subject to depth of array. (Almost COUNT_RECURSIVE, but you can point on which depth you want to plunge).
<?
function getArrCount ($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;
}
?>
anil dot iitk at gmail dot com
26-Jan-2006 05:32
26-Jan-2006 05:32
<?php
$food = array('fruits' => array('orange', 'banana', 'apple'),
'veggie' => array('carrot', 'collard', 'pea'));
// recursive count
echo "<br>".count($food, COUNT_RECURSIVE); // output 8
function average($a){
return array_sum($a)/count($a) ;
}
$b = array(1,2,3,4,5,6,7,8,9);
echo "Average of array:".average($b);
?>
Scorch at netpix dot com
20-Dec-2005 10:59
20-Dec-2005 10:59
Be careful of recasting your variables, especially with database array returns:
<?php
$res = mysql_query("select * from blah") // a query that returns an empty set
$row = mysql_fetch_array($res); // get's 0 since there's no return
echo count($row); // echos 1 - since $row is not an array
echo $row[0]; // echos "", but casts $row as an array?
echo count($row); // echos 0 now
?>
Tom
01-Dec-2005 09:57
01-Dec-2005 09:57
You can find an average from an array using this and array_sum.
<?php
//array average( array input )
function average($input) {
return array_sum($input) / count($input);
}
?>
You can also do a method of form validation that involves putting all errors into an array and letting count() do the key part.
<?php
if(isset($_POST['submit'])) {
$errors = array();
if(empty($_POST['message'])) $errors[] = "Empty message field";
if(!preg_match('/[a-z0-9.]@[a-z0-9].[a-z]/i', $_POST['email']) {
$errors[] = "Bad email address";
}
if(count($errors) == 0) {
//process form...
}
}
?>
Fred D
19-Oct-2005 01:16
19-Oct-2005 01:16
The trim_text function was helpful, but it did not take account of the possibility of having nothing to trim which can sometimes happen if you are using this function in a loop through data. I've added a count function to deal with that possibility
------------------------------
function trim_text_elipse($text, $count){
//Create variable
$trimmed="";
//Remove double white space
$text = str_replace(" ", " ", $text);
//Turn the text into an array
$string = explode(" ", $text);
//Check to see how many words there are
$wordTotal = count($string);
//Check to see if there are more words than the $count variable
if($wordTotal > $count){
//Loop through adding words until the $count variable is reached
for ( $wordCounter = 0; $wordCounter <= $count; $wordCounter++ ){
$trimmed .= $string[$wordCounter];
//Check to and add space or finish with elipse
if ( $wordCounter < $count ){ $trimmed .= " "; }
else { $trimmed .= " …"; }
}
}else{
//Set value returned to the existing value
$trimmed =$text;
}
//Trim off any white space
$trimmed = trim($trimmed);
return $trimmed;
}
-------------------------------
david _at_ webgroup _dot_ org
13-Feb-2005 09:30
13-Feb-2005 09:30
While michael at htmlland dot net's code works, I believe it is better to use:
$extension=substr($file,strrpos($file,".")+1);
This doesn't incur the overhead of array handling. I haven't tested it for time functions, but it should work just as well and SHOULD be faster.
freefaler at gmail dot com
20-Nov-2004 10:01
20-Nov-2004 10:01
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($food,0)); //output 6
?>
moazzam at ummah dot org
15-Oct-2004 08:59
15-Oct-2004 08:59
This is an obvious note, but I am writing it any way so other, who did may not have observed this, can take advantage of it too.
When running loops with count conditions, the code runs faster if you first assign the count() value to a variable and use that (instead of using count() directly in a loop condition.
To explain my point better, here is an example:
<?php
for ($i=0; $i<10000; $i++) {
$arr[] = $i;
}
$time11 = microtime_float();
$bf = "";
for ($i=0; $i<count($arr); $i++) {
$bf .= $arr[$i]."\n";
}
$time12 = microtime_float();
$time1 = $time12 - $time11;
print "First: ".$time1."\n";
$time21 = microtime_float();
$l = count($arr);
for ($i=0; $i<$l; $i++) {
$bf .= $arr[$i]."\n";
}
$time22 = microtime_float();
$time2 = $time22 - $time21;
print "Second: ".$time2."\n";
?>
The output from the code above is (when run many times):
First: 0.13001585006714
Second: 0.099159002304077
First: 0.12128901481628
Second: 0.079941987991333
First: 0.18690299987793
Second: 0.13346600532532
As you can see, the second method (which doesnt use count() directly in the loop) is faster than the first method (which uses count() directly in the loop).
BTW: I copied the microtime_float() function from one of the comments in the microtime() section. It just returns time with microseconds as float. Check comments in microtime() for more info.
michael at htmlland dot net
05-Jun-2004 02:30
05-Jun-2004 02:30
I have found on upload scripts or on file manipulation scripts that people can trick a classic file type filter:
example:
$filename="bob.jpg.wav";
$bits= explode(".",$filename);
$extention= $bits[1];
if($extention == "jpg"){ echo"Not correct"; exit; }
This returns the filename extention as jpg not wav.
One way to change this is to use count() :
example:
$filename="bob.jpg.wav";
$bits= explode(".",$filename);
$extention= $bits[count($bits) - 1];
if($extention == "jpg"){ echo"Not correct"; exit; }
This returns the filename extention as wav not jpg.
rolandfoxx at yahoo dot com
31-Mar-2004 09:13
31-Mar-2004 09:13
As an addition, any of the array manipulation functions can likewise get count to once again return 0:
<?php
$a = array();
print(count($a)); // prints 0
$a[0] = "foo";
array_shift($a);
print(count($a)); //prints 0
$a[0] = "bar";
array_splice($a, 0, 1);
print(count($a)); //prints 0
?>
admin at lft-muenchen dot de
12-Mar-2003 09:18
12-Mar-2003 09:18
Note:
print (strlen($a)); // will print 0
$a="";
print (strlen($a)); // will print 1
$a=null;
print (strlen($a)); // will print 1
$a=array();
print (strlen($a)); // will print 0
you can only get an array back to size 0 by using the array() command, not by just setting it to "" or null.
simon at invalid dot com
20-Aug-2002 04:40
20-Aug-2002 04:40
Reminder for using count():
<?php
$ary = array(null, "a", "b", null);
echo count($ary); // count: 4
$ary[10] = "c";
echo count($ary); // count: 5
$ary[15] = null;
echo count($ary); // count: 6
?>
=> NULL is seen as an element in count()
Count 2D array:
<?php
$a2Dary = array(array("a", "b") , array(), "v");
echo count($a2Dary); // count: 3
echo count($a2Dary[0]); //count 2
echo count($a2Dary[1]); // count: 0
echo count($a2Dary[2]); // count: 1
?>
Hope can help you
bryce at obviously dot com
23-Jul-2002 07:44
23-Jul-2002 07:44
If you're working with a database, you'll probably have much greater luck with: mysql_num_rows( $result );
09-Jul-2002 01:18
Perhaps change the wording of this description from "Count elements in a variable" to "Count total elements in a variable" as it may be interpreted (by me) as a function for counting specific elements (ie, number of substrings)
webmaster at NOSPAMtrafficg dot com
26-Apr-2002 07:48
26-Apr-2002 07:48
Counting a multi-dimentional array
test array
<?php
$settings[0][0] = 128;
$settings[0][1] = 256;
$settings[0][2] = 384;
$settings[0][3] = 512;
$settings[0][4] = 1024;
$settings[0][5] = 2048;
$settings[1][0] = 1024;
$settings[1][1] = 2048;
$settings[1][2] = 3072;
$settings[1][3] = 4096;
count($settings) // returns 2
count($settings[0]) // returns 6
count($settings[1]) // returns 4
?>
07-Feb-2002 11:01
<?php
count(false) ==1
?>
this has tripped me up before...
kanareykin at denison dot edu
27-Mar-2001 06:13
27-Mar-2001 06:13
Here's how to count non-empty elements
in an array of any dimension. Hope
it will be useful for somebody.
<?php
// recursively count all non-empty elements
// in array of any dimension or mixed - i.e.
// array('1' => 2, '2' => array('1' => 3, '2' => 4))
function count_all($arg)
{
// skip if argument is empty
if ($arg) {
// not an array, return 1 (base case)
if(!is_array($arg))
return 1;
// else call recursively for all elements $arg
foreach($arg as $key => $val)
$count += count_all($val);
return $count;
}
}
?>
martin at complinet dot com
30-Nov-2000 09:31
30-Nov-2000 09:31
The count function does not ignore null values in an array. To achieve this use this function.
<?php
function xcount($array) {
while (list($key, $value) = each($array)) {
if ($value) {
$count++;
}
}
return $count;
}
?>
jmcastagnetto at php dot net
05-Sep-2000 04:30
05-Sep-2000 04:30
If you want to disambiguate if a variable contains an array w/ only one element, just us is_array() or gettype()
legobuff at hotmail dot com
03-Feb-2000 03:43
03-Feb-2000 03:43
This is taken from sganer@expio.co.nz comments on the sizeof() function:
If some elements in your array are not set, then sizeof() and count() will not return the index of the last element, but will return the number of set elements. To find the index of the last element in the array:
end($yourArray);
$index = key($yourArray);
... Where $yourArray is the array you want to find the last index ($index) of.