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Array Funktionen

<<array_key_exists

array_map>>

array_keys

(PHP 4, PHP 5)

array_keysLiefert alle Schlüssel oder eine Teilmenge aller Schlüssel eines Arrays

Beschreibung

array array_keys ( array $input [, mixed $search_value [, bool $strict = false ]] )

array_keys() gibt die Schlüssel (numerisch und als String) des Arrays input zurück.

Ist der optionale Parameter search_value angegeben, werden nur die Schlüssel für diesen Wert zurückgegeben. Andernfalls werden alle Schlüssel von input zurückgegeben.

Parameter-Liste

input

Ein Array mit den zurückzugebenden Schlüsseln.

search_value

Wenn angegeben, werden nur Schlüssel mit diesen Werten zurückgegeben.

strict

Bestimmt, ob ein strikter Vergleich (===) während der Suche verwendet werden soll.

Rückgabewerte

Gibt ein Array mit allen Schlüssen des Arrays input zurück.

Changelog

Version Beschreibung
5.0.0 Der strict-Parameter wurde hinzugefügt.

Beispiele

Beispiel #1 array_keys()-Beispiel

<?php
$array 
= array(=> 100"Farbe" => "rot");
print_r(array_keys($array));

$array = array("blau""rot""grün""blau""blau");
print_r(array_keys($array"blau"));

$array = array("Farbe" => array("blau""rot""grün"),
               
"Größe" => array("klein""mittel""groß"));
print_r(array_keys($array));
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

Array
(
    [0] => 0
    [1] => Farbe
)
Array
(
    [0] => 0
    [1] => 3
    [2] => 4
)
Array
(
    [0] => Farbe
    [1] => Größe
)

Siehe auch


22 BenutzerBeiträge:
- Beiträge aktualisieren...
el dot quick at gmail dot com
23.09.2011 17:23
Sorry for my english...

I wrote a function to get keys of arrays recursivelly...

<?php
   
function recursive_keys($input, $search_value = null){

       
$output = ($search_value !== null ? array_keys($input, $search_value) : array_keys($input)) ;
        foreach(
$input as $sub){
            if(
is_array($sub)){
               
$output = ($search_value !== null ? array_merge($output, recursive_keys($sub, $search_value)) : array_merge($output, recursive_keys($sub))) ;
            }
        }
        return
$output ;
    }
?>

I hope it will be usefull

Regards
pat dot leblanc at gmail dot com
29.08.2011 23:05
It's worth noting that if you have keys that are long integer, such as '329462291595', they will be considered as such on a 64bits system, but will be of type string on a 32 bits system.

for example:
<?php

$importantKeys
= array('329462291595' =>null, 'ZZ291595' => null);

foreach(
array_keys($importantKeys) as $key){
    echo
gettype($key)."\n";
}

?>

will return on a 64 bits system:
<?php
    integer
    string
?>

but on a 32 bits system:
<?php
    string
    string
?>

I hope it will save someone the huge headache I had :)
rarioj at gmail dot com
5.10.2009 3:38
Sometimes we want to find out the last added numerical key right after we use " array_push($array, $value) " or " $array[] = $value ". This can be achieved by calling:

<?php
return array_pop(array_keys($array));
?>
ferrerna at gmail dot com
23.01.2009 18:14
Here's a function I needed to collapse an array, in my case from a database query.  It takes an array that contains key-value pairs and returns an array where they are actually the key and value.

<?php

function array_collapse($arr, $x, $y) {
   
$carr = array();
    while (
$el = current($arr)) {
       
$carr[ $el[$x] ] = $el[$y];
       
next($arr);
    }
    return
$carr;
}

?>

Example usage (pseudo-database code):

<?php

$query
= db_query('SELECT name, value FROM properties');

$result = db_returnAll($query);

/* This will return an array like so:

[
   ['name' -> 'color', 'value' -> 'blue'],
   ['name' -> 'style', 'value' -> 'wide-format'],
   ['name' -> 'weight', 'value' -> 3.6],
   ['name' -> 'name', 'value' -> 'Waerdthing']
]

*/

$propArr = array_collapse($result, 'name', 'value');

/* Now this array looks like:

[
   ['color' -> 'blue'],
   ['style' -> 'wide-format'],
   ['weight' -> 3.6],
   ['name' -> 'Waerdthing'],

*/

?>

I found this handy for using with json_encode and am using it for my project http://squidby.com
nodarinodo at mail dot ru
3.12.2008 20:35
<?php
   
//It's a way to get keys from values )
   
$es = array("is My FullName"=>"nodar chkuaselidze (nodarinodo)", "You Are" => "I don't know", "Is My Friend" => "ruxadze");
    foreach(
array_values($es) as $ess){
        echo
$ess." =>";
           
    for(
$i =0; $i < count(array_keys($es, $ess)); $i++){
            echo
reset(array_keys($es, $ess))."<BR>";
        } }
?>
neil at 11 out of 10
24.07.2008 9:10
<?php

/*
 * This function will return the keys of elements in the
 * haystack where the value is found in array needle
 */

function array_value_intersect_keys( $array_haystack, $array_needle ){
   
$intersected = array_intersect( $array_haystack, $array_needle );
    return
array_keys( $intersected );
}

// usage

$array_haystack = array( 1 => 2, 2 => 5, 'red' => 8, 9 => 14 );

$array_needle = array( 2, 8 );

$array_keys_of_intersecting_values = array_value_intersect_keys( $array_haystack, $array_needle );

print_r( $array_keys_of_intersecting_values );
?>

returns
Array
(
    [0] => 1
    [1] => red
)
edsongarrido at gmail dot com
12.06.2008 14:46
/*
*
*This function will return a .csv from a given array inside the $_SESSION['my_array']
*
*$csv_name -> the name we want the csv has to
*$download -> true or false to download the csv file after done
*
*/

<?php

function createCSV($csv_name, $download) {

       
$i = 1;
       
$csv = "";

       
/* erase the old file, if it exists */
       
@unlink("../../csv/" . $csv_name . ".csv");

       
/* array is in a session variable
         * this may be useful to avoid many db queries if it is the case */
       
$my_array = $_SESSION['my_array'];

       
/* how many fields has the given array */
       
$fields = count(array_keys($my_array[0]));

       
/* extracting the titles from the array */
       
foreach(array_keys($my_array[0]) as $title)
        {
           
/* array_keys percurs the title of each vector */
           
$csv .= $title;

           
/* while it is not the last field put a semi-colon ; */
           
if($i < $fields)
               
$csv .= ";";

           
$i++;
        }

       
/* insert an empty line to better visualize the csv */
       
$csv .= chr(10).chr(13);
               
$csv .= chr(10).chr(13);

       
/* get the values from the extracted keys */
       
foreach (array_keys($my_array) as $tipo)
        {

           
$i = 1;

            foreach(
array_keys($my_array[$tipo]) as $sub)
            {

               
$csv .= $my_array[$tipo][$sub];

                if (
$i < $fields)
                   
$csv .= ";";

               
$i++;
            }

           
$csv .= chr(10).chr(13);

        }

       
/* export the csv */
       
$export_csv=fopen("../../csv/". $csv_name .".csv", "w+");
       
fwrite($export_csv, $csv);
       
fclose($export_csv);

       
/* download the csv */
       
if ($download == true)
           
header('Location:' . "../../csv/" . $csv_name . ".csv");

        exit();

    }

?>
Hayley Watson
5.10.2007 3:43
An alternative to RQuadling at GMail dot com's array_remove() function:

<?php
function array_remove(array $array, $value, $strict=false)
{
    return
array_diff_key($array, array_flip(array_keys($array, $value, $strict)));
}
?>
RQuadling at GMail dot com
28.03.2007 15:31
If you want to remove a value from an array, then there is no direct mechanism.

The following function uses the array_keys() function to find the key(s) of the value that you want to remove and then removes the elements for that key.

I've also given some examples and the output.

<?php
/**
  * array array_remove ( array input, mixed search_value [, bool strict] )
  **/
function array_remove(array &$a_Input, $m_SearchValue, $b_Strict = False) {
   
$a_Keys = array_keys($a_Input, $m_SearchValue, $b_Strict);
    foreach(
$a_Keys as $s_Key) {
        unset(
$a_Input[$s_Key]);
    }
    return
$a_Input;
}
?>

Beside scalar variables (integers, floats, strings, boolean), you can also use arrays as the values you want to remove.

<?php
// Results in array(8, 8.0, '8', '8.0')
array_remove(array(8, 8.0, '8', '8.0', array(8), array('8')), array(8));

// Results in array(8, 8.0, '8', '8.0', array('8'))
array_remove(array(8, 8.0, '8', '8.0', array(8), array('8')), array(8), True);
?>
creator at mindcreations dot com
20.03.2007 11:12
This function will extract keys from a multidimensional array

<?php
function multiarray_keys($ar) {
           
    foreach(
$ar as $k => $v) {
       
$keys[] = $k;
        if (
is_array($ar[$k]))
           
$keys = array_merge($keys, multiarray_keys($ar[$k]));
    }
    return
$keys;
}
?>

Example code:

<?php
$array
= array("color" => array("1stcolor" => "blue", "2ndcolor" => "red", "3rdcolor" => "green"),
              
"size"  => array("small", "medium", "large"));

echo
"<pre>";
print_r($array);
echo
"</pre>";

echo
"<pre>";
print_r(multiarray_keys($array));
echo
"</pre>";
?>

Example output:

Array
(
    [color] => Array
        (
            [1stcolor] => blue
            [2ndcolor] => red
            [3rdcolor] => green
        )

    [size] => Array
        (
            [0] => small
            [1] => medium
            [2] => large
        )

)

Array
(
    [0] => color
    [1] => 1stcolor
    [2] => 2ndcolor
    [3] => 3rdcolor
    [4] => size
    [5] => 0
    [6] => 1
    [7] => 2
)
Ray.Paseur sometimes uses GMail
21.12.2006 13:38
Replace a key in an associative array, preserving the original order of keys and elements:

<?php
if (!function_exists('array_combine')) { // ONLY EXISTS IN PHP5
   
function array_combine($keys, $values) {
        if (
count($keys) != count($values)) {
    return
false; }
        foreach(
$keys as $key) { $array[$key] = array_shift($values); }
    return
$array; }   
}
// END IF FUNCTION EXISTS

$keys = array_keys($array);
$values = array_values($array);
foreach (
$keys as $k => $v) {
    if (
$v == "MANAGEMENT FEE CHARGE") { $keys[$k] = "MANAGEMENT FEES"; }
}
$array = array_combine($keys, $values);
?>
jochem
18.02.2006 1:13
might be worth noting in the docs that not all associative (string) keys are a like, output of the follow bit of code demonstrates - might be a handy introduction to automatic typecasting in php for some people (and save a few headaches):

<?php
$r
= array("0"=>"0","1"=>"1","" =>"2"," "=>"3");
echo
'how php sees this array: array("0"=>"0","1"=>"1","" =>"2"," "=>"3")',"\n-----------\n";
var_dump($r); print_r($r); var_export($r);
echo
"\n-----------\n",'var_dump("0","1",""," ") = ',"\n-----------\n";
var_dump("0","1",""," ");
?>

OUTPUTS:

how php sees this array: array("0"=>"0","1"=>"1","" =>"2"," "=>"3")
-----------
array(4) {
  [0]=>
  string(1) "0"
  [1]=>
  string(1) "1"
  [""]=>
  string(1) "2"
  [" "]=>
  string(1) "3"
}
Array
(
    [0] => 0
    [1] => 1
    [] => 2
    [ ] => 3
)
array (
  0 => '0',
  1 => '1',
  '' => '2',
  ' ' => '3',
)
-----------
var_dump("0","1",""," ") =
-----------
string(1) "0"
string(1) "1"
string(0) ""
string(1) " "
Sven (bitcetera.com)
19.12.2005 15:43
Here's how to get the first key, the last key, the first value or the last value of a (hash) array without explicitly copying nor altering the original array:

<?php
  $array
= array('first'=>'111', 'second'=>'222', 'third'=>'333');

 
// get the first key: returns 'first'
 
print array_shift(array_keys($array));

 
// get the last key: returns 'third'
 
print array_pop(array_keys($array));

 
// get the first value: returns '111'
 
print array_shift(array_values($array));

 
// get the last value: returns '333'
 
print array_pop(array_values($array));
?>
vesely at tana dot it
9.12.2005 10:56
The position of an element.

One can apply array_keys twice to get the position of an element from its key. (This is the reverse of the function by cristianDOTzuddas.) E.g., the following may output "yes, we have bananas at position 0".

<?php
$a
= array("banana" => "yellow", "apple" = "red");
$k = get_some_fruit();
if (isset(
$a[$k]))
{
   list(
$pos) = array_keys(array_keys($a), $k);
   print
"yes, we have {$k}s at position $pos\n";
}
?>

Not amazingly efficient, but I see no better alternative.
ru dot dy at gmx dot net
14.08.2005 18:20
I was looking for a function that simply unset a variable amout of values from a one-dimensional array by key. I ended up with this (returns the array itself if no further parameter than the array is given, false with no params - does not change the source array)

usage: array_remove(array $input [, mixed key ...])

<?php

 
function array_remove() {
    if (
$stack = func_get_args()) {
     
$input = array_shift($stack);
      foreach (
$stack as $key) {
        unset(
$input[$key]);
      }
      return
$input;
    }
    return
false;
  }

?>

Test:

<?php
  $a
= array('a'=>'fun', 'b'=>3.14, 'sub'=> array('1', '2', '3'), 'd'=>'what', 'e' => 'xample', 5 => 'x');
 
print_r($a);
 
print_r(array_remove($a, 'd', 'b', 5, 'sub'));
?>

Output:

Array
(
    [a] => fun
    [b] => 3.14
    [sub] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
        )

    [d] => what
    [e] => xample
    [5] => x
)
Array
(
    [a] => fun
    [e] => xample
)

Hope this helps someone.
alex [@T] d-sn [D@T] com / Alex Galisteo
7.08.2005 11:46
My version of PHP does not support the strict parameter. Moreover, I need a function that could make other comparsion different than equals and stricktly equals.

The funcition array_keys_advanced can make the following comparsions: equal, not equal, strictly greater than, equal or greater than, strictly less than, equal or less than.

<?php
if (!function_exists('array_keys_advanced')) {
   
//{{{ array_keys_advanced
    /**
     * Returns an array with the matching keys as values. A comparsion type can
     * be spcified, even if it should be a strict comparsion or not.
     * Note: It is not recursive.
     *
     * @param    array    $input
     * @param    string   $search_value
     * @param    bool     $strict
     * @param    string   $comparison: {EQ | NEQ | GT | EGT | LT | ELT}
     * @return   Returns an array with the matching keys as values.
     * @author   alex [@T] d-sn [D@T] com // Alex Galisteo
     */
   
function array_keys_advanced() {
       
$nargs = func_num_args();
       
$arr = array();
       
$input = null;
       
$search_value = null;
       
$strict = (bool) false;
       
$comparison  = "EQ";
       
$comparsion_types = array("EQ", "NEQ", "GT", "EGT", "LT", "ELT");
        switch (
$nargs) {
        case
1:
           
$input = func_get_arg(0);
            return
array_keys($input);
            break;
        case
2:
           
$input = func_get_arg(0);
           
$search_value = func_get_arg(1);
            return
array_keys($input, $search_value);
            break;
        case
3:
           
$input = func_get_arg(0);
           
$search_value = func_get_arg(1);
           
$strict = (bool) func_get_arg(2);
           
$comparsion  = "EQ";
            break;
        case
4:
           
$input = func_get_arg(0);
           
$search_value = func_get_arg(1);
           
$strict = (bool) func_get_arg(2);
           
$comparsion = strtoupper((string) func_get_arg(3));
           
$comparsion = (in_array($comparsion, $comparsion_types))?
                           
$comparsion : "EQ";
            break;
        default:
            return
$arr;
            break;
        }
        foreach (
$input as $key => $val) {
            if (
$strict) {
                if (
$comparsion == "EQ" && $search_value === $val) {
                   
$arr[] = $key;
                }
                elseif (
$comparsion == "NEQ" && $search_value !== $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "GT" && $search_value > $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "EGT" && $search_value >= $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "LT" && $search_value < $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "ELT" && $search_value <= $val)
                   
$arr[] = $key;
            } else {
                if (
$comparsion == "EQ" && $search_value == $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "NEQ" && $search_value != $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "GT" && $search_value > $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "EGT" && $search_value >= $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "LT" && $search_value < $val)
                   
$arr[] = $key;
                elseif (
$comparsion == "ELT" && $search_value <= $val)
                   
$arr[] = $key;
            }
        }
        return
$arr;
    }
   
//}}}
} //endif function_exists
?>
webmaster [at] baz-x [dot] at
30.07.2005 0:43
I was looking for a function that deletes either integer keys or string keys (needed for my caching).
As I didn't find a function I came up with my own solution.
I didn't find the propiest function to post to so I will post it here, hope you find it useful.

<?php

function array_extract($array, $extract_type = 1)
{
    foreach (
$array as $key => $value )
    {
        if (
$extract_type == 1 && is_string($key) )
        {
           
// delete string keys
           
unset($array[$key]);
        }
        elseif (
$extract_type == 2 && is_int($key) )
        {
           
// delete integer keys
           
unset($array[$key]);
        }
    }

    return
$array;
}

?>

You can of course define constants to have a nicer look, I have chosen these: EXTR_INT = 1; EXTR_STRING = 2
EXTR_INT will return an array where keys are only integer while
EXTR_STRING will return an array where keys are only string

Have fun with it.
sip at email dot ee
22.08.2003 14:33
Note, that using array_key_exists() is rather inefficient. The overhead associated with calling a function makes it slower, than using isset($array[$key]), instead of array_key_exists($key, $array)
using isset() is usually about 1.3 times faster, according to my tests.
rodrigo at NOSPAM dot dhweb dot com dot br
5.02.2003 1:39
[Editor's note: For a complete solution to the printing of complex structures or hashes, see the PEAR::Var_Dump package: http://pear.php.net/package-info.php?pacid=103 , use "pear install Var_Dump" to get it]

This function will print all the keys of a multidimensional array in html tables.
It will help to debug when you dont have control of depths.

<?php
function show_keys($ar){

   echo
"<table width='100%' border='1' bordercolor='#6699CC' cellspacing='0' cellpadding='5'><tr valign='top'>";

      foreach (
$ar as $k => $v ) {

         echo
"<td align='center' bgcolor='#EEEEEE'>
           <table border='2' cellpadding='3'><tr><td bgcolor='#FFFFFF'><font face='verdana' size='1'>
              "
. $k . "
           </font></td></tr></table>"
;

           if (
is_array($ar[$k])) {
             
show_keys ($ar[$k]);
         }

         echo
"</td>";

      }

   echo
"</tr></table>";

}

// Multidimensional array ->
$arvore = array();
$arvore['1'] = array();
$arvore['1']['1.1'] = array('1.1.1', '1.1.2', '1.1.3');
$arvore['1']['1.2'] = array('1.2.1', '1.2.2', '1.2.3');
$arvore['1']['1.3'] = array('1.3.1', '1.3.2', '1.3.3');
$arvore['2'] = array();
$arvore['2']['2.1'] = array('2.1.1', '2.1.2', '2.1.3');
$arvore['2']['2.2'] = array('2.2.1', '2.2.2', '2.2.3');
$arvore['2']['2.3'] = array('2.3.1', '2.3.2', '2.3.3');
$arvore['3'] = array();
$arvore['3']['3.1'] = array('3.1.1', '3.1.2', '3.1.3');
$arvore['3']['3.2'] = array('3.2.1', '3.2.2', '3.2.3');
$arvore['3']['3.3'] = array('3.3.1', '3.3.2'=>array('3.3.2.1', '3.3.2.2'), '3.3.3');
// <-

show_keys($arvore);
?>
michielbakker at msn dot com
13.11.2002 18:45
If you receive a bunch of variables and like to change most of them (or all of them for that matter), you can do something like this: (data has been sent to a page with POST)

<?php
$allKeys
= array_keys($HTTP_POST_VARS);

for (
$i=0;$i<count($allKeys);$i++)
{
      $
$allKeys[$i] = strtoupper($HTTP_POST_VARS[$allKeys[$i]]);
}
?>

This makes caracters (a-z) uppercase. This is just one way to use it, ofcourse.

Hope this helps someone understand the way to use array_keys() or give any ideas. :)
glennh at webadept dot net
13.11.2002 13:03
All the cool notes are gone from the site.

Here's an example of how to get all the variables passed to your program using the method on this page. This prints them out so you can see what you are doing.

<?php
while (list($key, $value) = each
(${"HTTP_".$REQUEST_METHOD."_VARS"}))
{
        echo
$key." = ".$value." ";
}
?>
jacob at keystreams dot com
21.08.2002 8:05
Here is a way to use array_intersect on array keys rather than values:

<?php
$a
= array("apple" => "red", "banana" => "yellow");
$z = array("apple" => "green", "peach" => "orange", "banana" => "rotten");

$intersected_keys = array_intersect(array_keys($a), array_keys($z));

print_r($intersected_keys);
?>

This will print:

Array ( [0] => apple [1] => banana )



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