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array_key_exists

(PHP 4 >= 4.1.0, PHP 5)

array_key_exists -- Проверить, присутствует ли в массиве указанный ключ или индекс

Описание

bool array_key_exists ( mixed key, array input )

Функция array_key_exists() возвращает TRUE, если в массиве присутствует указанное значение ключ. Параметр ключ может быть любым значением, которое подходит для описания индекса массива.

Пример 1. Пример использования array_key_exists()

$search_array = array("first" => 1, "second" => 4);
if (array_key_exists("first", $search_array)) {
    echo "The 'first' element is in the array";
}

Замечание: В PHP версии 4.0.6 название этой функции - key_exists().

См.также isset().



array_keys> <array_intersect
Last updated: Sat, 27 Jan 2007
 
add a note add a note User Contributed Notes
array_key_exists
albertid
24-Oct-2007 03:25
Here my proposal for an "array_keys_exist":

function array_keys_exist($keys, $array)
{
  return (sizeof(array_diff(array_keys($array), $keys)) == 0);
}
wolf550e at gmail dot com
27-Sep-2007 12:51
array_key_exists(), at least in 5.2.4, passes the array by value. I conclude this from seeing performance worsen as the array to search got bigger. isset() doesn't have this problem.
diogoshaw at gmail dot com
15-Sep-2007 11:58
this function very good to use if you need to verify many variables:

<?php
function array_key_exists_r($keys, $search_r) {
    $keys_r = split('\|',$keys);
    foreach($keys_r as $key)
    if(!array_key_exists($key,$search_r))
    return false;
    return true;
}
?>

e.g.

<?php
if(array_key_exists_r('login|user|passwd',$_GET)) {
// login
} else {
// other
}
?>

works for me, enjoy.
dg shaw.
j_hattersleydykes {at} yahoo uk
26-Aug-2007 05:39
hey - I thought this function maybe useful to someone somewhere..
It works on an array of the keys you want to check exist. you could pass in the names of form fields and the POST array - suppose it could be useful in aiding form validation.

function array_keys_exist(array $keys, array $toCheck, $whichKey = false)
{
    foreach ($keys as $array_key)
    {
        if (! array_key_exists($array_key, $toCheck))
        {
            // return first key thats not found.
            if ($whichKey)
            {
                return $array_key;
            }
            else
            {
                return false;
            }
        }
    }
    // all keys exist
    return true;
}

hope someone finds it useful :)
sj-b at hotmail dot de
31-Jul-2007 09:14
i dont like how empty() works.
an integer with value 0 or a boolean wth
value false (same like zero) counts as
empty too.

[code]function r_empty (&$check)
{
    if (!isset($check)) return true;
    if ($check == NULL) return true;
    return false;
}[/code]

that is a good replacement for
both functions for me.
Lucknut dot xbl at googlemail dot com
18-Jul-2007 10:44
I found this function very good to use if your want your urls like index.php?login or index.php?register
e.g.
<?php
if( array_key_exists( 'home',$_GET ) ) {
    echo "Home - its where the heart is.";
} else if( array_key_exists( 'login',$_GET ) ) {
    echo "Login code here!";
} else if( array_key_exists( 'register',$_GET ) ) {
    echo "Register code here!";
} else {
    echo "Home - its where the heart is.";
}
?>
david at madole dot net
05-Jul-2007 08:11
Regarding performance differences between isset() and array_key_exists(), the differences may be there, but the function are not always interchangable.

Note that when $a[1] = null then isset($a[1]) == false but array_key_exists(1, $a) == true
eidberger at jakota dot de
11-Jun-2007 01:14
Just wondered why array_key_exists() makes me a cpu-load of 85% while isset() only needs 35%.

Not a big thing for one time execution, but in my case it have to check 1-dimensional array with ~ 15.000 entries 100 times a second. My code checks a big array for existing entrys and updates them, if needed.

Hopes it helps somebody. Notice that on many other functions, which makes coding more comfortable at the cost of speed.
alishahnovin at hotmail dot com
28-May-2007 10:47
Seems the array_key_exists can't find a key in a multidimensional array...

Here's my fix...

<?php

function multi_array_key_exists($needle, $haystack) {
  foreach ($haystack as $key=>$value) {
    if ($needle==$key) {
      return true;
    }
    if (is_array($value)) {
      multi_array_key_exists($needle, $value);
    }
  }
  return false;
}

?>
php at ianco dot co dot uk
09-Apr-2007 01:58
array_key_exists is case sensitive (at least in PHP 4.3.9). To make a case-insensitive comparison you could use strtolower on both sides.
inker2576 at yahoo dot com
06-Mar-2007 08:01
Further research on this has turned up that the performance problems are a known, confirmed bug in PHP 5.1.x, and have been fixed in PHP builds after September 2006.  You can find the bug report here:  http://bugs.php.net/bug.php?id=38812

However, just because it's a fixed bug doesn't really change the conclusion.  If you're writing a script and there's any chance it could be used on a PHP 5.1.x server, you should still avoid this function and use isset() or some other kind of test if you want it to run efficiently.
serkan yersen
07-Feb-2007 04:01
marzetti.marco,
I fixed your function it's is more optimized and working better now.

function regex_array_keys($arr, $pattern){
   $results[] = false;

   if(!is_array($arr))
       return false;

   foreach($arr as $key => $val){
         if(!is_array($key))
       if(preg_match($pattern,$key))
              array_push($results,$key);
   }

   return $results;
}
brauliorossi at gmail dot com
25-Jan-2007 09:42
Matt and mikael dot knutsson at gmail dot com:

this outputs bool(true):

$ar = array ( 'outter' => array ( 'inner' => 1 ) );
var_dump(array_key_exists('inner', $ar['outter']));
mikael dot knutsson at gmail dot com
15-Dec-2006 10:50
You're right, I'm not sure what I did wrong since I had a problem where array_key_exists returned true, while
<?php
$keys = array_keys( $array );
var_dump( in_array( 'key', $keys ) );
?>
returned false. (Which does the exact same thing) I probably either messed up the array, or the order in one of the array calls.
I rewrote the entire section where I had this problem (which was probably a good idea anyway), so I don't have any demonstration code.
Matt
01-Dec-2006 01:50
mikael dot knutsson at gmail dot com:
I don't think it does, at least in PHP5?

For example, this outputs bool(false):

$ar = array ( 'outter' => array ( 'inner' => 1 ) );
var_dump(array_key_exists('inner', $ar));

So it doesn't actually check the inner array for the key 'inner'.
mikael dot knutsson at gmail dot com
24-Nov-2006 04:05
When dealing with multi-dimensional arrays, this function checks through all keys in the array, including the "child arrays" unlike the array_keys( array, $search ) function which would only check and return from the first level of keys.

Took me a couple of minutes to figure out what was wrong and I hope it helps some people when looking for the right function.
Mike Toppa
03-Aug-2006 10:43
At least in PHP 4.4.0, array_key_exists is inconsistently sensitive to different data types. For example, if your first argument is a double and the keys in your array are integers, array_key_exists will always return false. If you then cast the first argument to an integer, or even to a string, then you can successfully match. I haven't tested all the possibilities, to see when it'll tolerate different data types and when it won't, so the easiest and safest solution is to cast your first argument to match the data type of the keys.
ncurtis at cenicola-helvin dot com
09-Jul-2006 03:25
array_key_exists() does not check values in the key i wrote this function to check if a key in an array has a empty value as corresponds to values that return true for empty() an redirects to a page if specified otherwise returns false

<?php
function keysExists($array, $startingIndex, $redirectPage) {
    if(is_array($array)) {
        if (!empty($startingIndex)) {
            for ($i = 0; $i < $startingIndex; $i++) {
                next($array);
            }
        }
        while(list($key, $value) = each($array)) {
            if (empty($value)) {
                if (!empty($redirectPage)) {
                    header("Location: $redirectPage");
                } else {
                    return FALSE;
                }
            }
        }
    } else {
        return FALSE;
    }
}
?>
email me and let me no if you found this useful!
marzetti.marco at gmail.com
06-Jul-2006 02:44
Returns the keys in $arr matching $pattern in a regex

<?php

function regex_array_keys ( &$arr, $pattern ) {
    $results[] = false;
    if( !is_array( $arr ) )
        return false;
   
    while( !is_null( $key = key( $arr ) ) ) {
       
        if( preg_match( $pattern, $key ) )
            $results[] = $key;
        next($arr);
    }
    reset( $arr );
   

    return $results;
}

?>
09-May-2006 08:44
property_exists() does the same thing for object properties.
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array_keys> <array_intersect
Last updated: Sat, 27 Jan 2007
 
 
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