Diese Seite bei php.net
The PHP manual text and comments are covered by the Creative Commons Attribution 3.0 License © the PHP Documentation Group - Impressum - mail("TO:Reinhard Neidl",...)
(PHP 4, PHP 5)
count — Zählt alle Elemente eines Arrays oder Attribute eines Objekts
Zählt alle Elemente eines Arrays oder Attribute eines Objekts.
Wenn Sie die SPL installiert haben, können Sie in Objekten eine count()-Funktion nutzen, indem Sie das Interface Countable implementieren. Das Interface hat exakt eine Methode, nämlich count(), die den Rückgabewert der Funktion count() zurückliefert.
In der Sektion Arrays finden Sie eine detaillierte Erklärung, wie Arrays in PHP implementiert sind und wie sie benutzt werden.
Das Array.
Wenn der optionale Parameter mode auf COUNT_RECURSIVE (oder 1) gesetzt ist, wird count() rekursiv durch das Array zählen. Dies kann besonders nützlich sein, um alle Elemente eines mehrdimensionalen Arrays zu zählen. Der Standardwert für mode ist 0. count() erkennt keine endlose Rekursion.
Liefert die Anzahl von Elementen in var, welches typischerweise ein Array ist, da alles andere ein Element enthält.
Ist var kein Array oder Objekt mit Interface Countable, wird 1 zurückgegeben. Es besteht eine Ausnahme, wenn var NULL ist, in diesem Fall wird 0 zurückgegeben.
count() gibt 0 zurück, wenn die Variable nicht gesetzt ist, aber sie gibt ebenfalls 0 zurück, wenn die Variable als leeres Array initialisiert wurde. Verwenden Sie isset() um zu testen, ob eine Variable gesetzt ist.
| Version | Beschreibung |
|---|---|
| 4.2.0 | Der optionale Parameter mode wurde hinzugefügt. |
Beispiel #1 count()-Beispiel
<?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
?>
Beispiel #2 Rekursives count()-Beispiel
<?php
$food = array('Obst' => array('Orange', 'Banane', 'Apfel'),
'Gemüse' => array('Karotte', 'Kohl', 'Erbse'));
// rekursiv zählen
echo count($food, COUNT_RECURSIVE); // gibt 8 aus
// normales zählen
echo count($food); // gibt 2 aus
?>
Just found use for this function...
Can count an array of items where a certain condition is met.
Feel free to improve it.
function countWhere($input = 1, $operator = '==', $where = 1)
{
$input = is_array($input) ? $input : (array)$input;
$operator = !in_array($operator, array('<','>','<=', '>=','==', '!=')) ? '==' : $operator;
$i = 0;
foreach($input as $current)
{
$match = null;
eval('$match = (bool)("'.$current.'"'.$operator.'"'.$where.'");');
$i = $match ? $i+1 : $i;
}
return $i;
}
USAGE:
echo countWhere(array('PZ','AB','CD','EF','GH'), '!=', 'GH');
OUTPUT:
4
There was a change in a PHP5 version. Now an empty string returns 1:
<?php
echo count(''); // returns 1
echo count(array()); // returns 0
?>
This wasn't in PHP4 and some older PHP5 versions.
To know how much properties an object has, I do it like this:
count((array) $object)
... because count($object) gives me allways 1
The code snippet posted by legobuff at hotmail dot com on 02-Feb-2000 contains an error. This is the code that was posted:
<?php
// To find the index of the last element in the array:
end($yourArray);
$index = key($yourArray);
?>
However, this will fail if the indices have been stored out of sequence. What you actually want is max(array_keys($yourArray)), as indicated below:
<?php
$yourArray = array(1=>'a', 7=>'b', 5=>'c');
print count($yourArray); // prints 3
end($yourArray);
print key($yourArray); // prints 5
print max(array_keys($yourArray)); // prints 7
?>
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 {$cols} columns in the table!";
?>
There doesn't seem to be a succinct method already noted on this page for counting multidimensional array end nodes (Items in multidimensional arrays), so I thought this function might help somebody.
Nice and simple :)
<?php
function rcount ($array) {
$count = 0;
if (is_array($array)) {
foreach($array as $id=>$sub) {
if (!is_array($sub)) { $count++; }
else { $count = ($count + rcount($sub)); }
}
return $count;
}
return FALSE;
}
?>
I found useful this little function that detects if a array is multidimensional or not.
<?php
function array_is2D($array) {
return is_array($array) ? count($array)===count($array, COUNT_RECURSIVE) : -1;
}
?>
---
live2code
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;
}
?>
Please note: While SPL is compiled into PHP by default starting with PHP 5, the Countable interface is not available until 5.1
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;
}
?>
NEVER USE IN CYCLES!
<?php
//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.
<?php
// 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 $count;
}
?>
My function returns the number of elements in array for multidimensional arrays subject to depth of array. (Almost COUNT_RECURSIVE, but you can point on which depth you want to plunge).
<?php
function getArrCount ($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;
}
?>
<?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);
?>
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
?>
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...
}
}
?>
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
<?php
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;
}
?>
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.
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($food,0)); //output 6
?>
This is an obvious note, but I am writing it any way so other, who did may not have observed this, can take advantage of it too.
When running loops with count conditions, the code runs faster if you first assign the count() value to a variable and use that (instead of using count() directly in a loop condition.
To explain my point better, here is an example:
<?php
for ($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.
I have found on upload scripts or on file manipulation scripts that people can trick a classic file type filter:
example:
<?php
$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:
<?php
$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.
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($a)); //prints 0
?>
Note:
<?php
print (strlen($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.
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
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
?>
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 $count;
}
}
?>
The count function does not ignore null values in an array. To achieve this use this function.
<?php
function xcount($array) {
while (list($key, $value) = each($array)) {
if ($value) {
$count++;
}
}
return $count;
}
?>
If you want to disambiguate if a variable contains an array w/ only one element, just us is_array() or gettype()
This is taken from sganer@expio.co.nz comments on the sizeof() function:
If some elements in your array are not set, then sizeof() and count() will not return the index of the last element, but will return the number of set elements. To find the index of the last element in the array:
end($yourArray);
$index = key($yourArray);
... Where $yourArray is the array you want to find the last index ($index) of.
Diese Seite bei php.net