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array_search

(PHP 4 >= 4.0.5, PHP 5)

array_search --  在数组中搜索给定的值，如果成功则返回相应的键名

说明

mixed array_search ( mixed needle, array haystack [, bool strict] )

在 haystack 中搜索 needle 参数并在找到的情况下返回键名，否则返回 FALSE。

注: 如果 needle 是字符串，则比较以区分大小写的方式进行。

注: 在 PHP 4.2.0 之前，array_search() 在失败时返回 NULL 而不是 FALSE。

如果可选的第三个参数 strict 为 TRUE，则 array_search() 还将在 haystack 中检查 needle 的类型。

如果 needle 在 haystack 中出现不止一次，则返回第一个匹配的键。要返回所有匹配值的键，应该用 array_keys() 加上可选参数 search_value 来代替。

例子 1. array_search() 例子

<?php
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');

$key = array_search('green', $array); // $key = 2;
$key = array_search('red', $array);   // $key = 1;
?>

警告

本函数可能返回布尔值 FALSE，但也可能返回一个与 FALSE 等值的非布尔值，例如 0 或者 ""。请参阅布尔类型章节以获取更多信息。应使用 === 运算符来测试本函数的返回值。

参见 array_keys()，array_values()，array_key_exists() 和 in_array()。


add a note add a note User Contributed Notes
dmitry dot polushkin at gmail dot com
22-Oct-2006 01:03
To get the key of the found search value, use:
<?php
$a = array('a', 'b', 'c');
echo array_search(array_search('c', $a), array_keys($a));
?>
jupiter at nospam dot com
29-Sep-2006 05:25
Checks that array value STARTS with the string(needle), while other functions require an exact match OR the needle can be anywhere within.  This function can be manipulated to END with the needle if needed
<?php
// returns first key of haystackarray which array valuestring starts with needlestring, is case-sensitive
function arrayHaystackStartsWithNeedleString($haystackarray, $needlestring) {
   if (is_array($haystackarray)) {  // confirms array
       $needlelength = strlen($needlestring);  // length of string needle
       foreach ($haystackarray as $arraykey => $arrayvalue) {  // gets array value
           $arraypart = substr($arrayvalue, 0, $needlelength);  // first characters of array value
           if ($needlestring == $arraypart) {  // did we find a match
               return $arraykey;  // return will stop loop
           }  // end match conditional
       }  // end loop
   }  // end array check
   return false;  // no matches found if this far
}
?>
I haven't speed tested this, but it should be pretty quick.
Digitally Designed dot co dot uk
28-Sep-2006 05:48
My Function to search a Multidimensional array.

Pass in :

$theNeedle as what you want to find.
$theHaystack as the array
$keyToSearch as what key in the array you want to find the value in.

<?   

function myMulti_Array_Search($theNeedle, $theHaystack, $keyToSearch)
       {
       foreach($theHaystack as $theKey => $theValue)
           {
           $intCurrentKey = $theKey;   
              
           if($theValue[$keyToSearch] == $theNeedle)
               {
  
               return $intCurrentKey ;
               }
           else
               {
               return 0;
               }
           }
       }

?>
lars-magne
22-Sep-2006 08:19
Further comments on the multidimensional array searches given earlier:

I needed an extended search function which could search in both keys and values in any # dimension array and return all results. Each result contains key/value hit, type (key or value), key path and value (in case result is a key).

<?php

function array_search_ext($arr, $search, $exact = true, $trav_keys = null)
{
  if(!is_array($arr) || !$search || ($trav_keys && !is_array($trav_keys))) return false;
  $res_arr = array();
  foreach($arr as $key => $val)
  {
   $used_keys = $trav_keys ? array_merge($trav_keys, array($key)) : array($key);
   if(($key === $search) || (!$exact && (strpos(strtolower($key), strtolower($search)) !== false))) $res_arr[] = array('type' => "key", 'hit' => $key, 'keys' => $used_keys, 'val' => $val);
   if(is_array($val) && ($children_res = array_search_ext($val, $search, $exact, $used_keys))) $res_arr = array_merge($res_arr, $children_res);
   else if(($val === $search) || (!$exact && (strpos(strtolower($val), strtolower($search)) !== false))) $res_arr[] = array('type' => "val", 'hit' => $val, 'keys' => $used_keys, 'val' => $val);
  }
  return $res_arr ? $res_arr : false;
}

// I.e.:
$haystack[754] = "Norwegian";
$haystack[28]['details']['Norway'] = "Oslo";
$needle = "Norw";

if($results = array_search_ext($haystack, $needle, false))
  foreach($results as $res)
   echo "Found '$needle' in $res[type] '$res[hit]', using key(s) '".implode("', '", $res['keys'])."'. (Value: $res[val])<br />\n";

/* Printed result will be:
Found 'Norw' in val 'Norwegian', using key(s) '754'. (Value: Norwegian)
Found 'Norw' in key 'Norway', using key(s) '28', 'details', 'Norway'. (Value: Oslo)
*/

?>
mark dot php at mhudson dot net
12-Sep-2006 08:49
I was going to complain bitterly about array_search() using zero-based indexes, but then I realized I should be using in_array() instead.

// if ( isset( $_GET['table'] ) and array_search( $_GET['table'], $valid_tables) ) {  // BAD: fails on first[0] element
// if ( isset( $_GET['table'] ) and ( FALSE !== array_search( $_GET['table'], $valid_tables) ) ) { OK: but wasteful and convoluted
   if ( isset( $_GET['table'] ) and in_array( $_GET['table'], $valid_tables) ) { // BETTER

The essence is this: if you really want to know the location of an element in an array, then use array_search, else if you only want to know whether that element exists, then use in_array()
ob at babcom dot biz
28-Aug-2006 05:55
This function is based on the function in comment "array_search" from July 26th 2006.

I added the possibility of defining the key which $Needle shall be searched for.

<?php
// search haystack for needle and return an array of the key path,
// FALSE otherwise.
// if NeedleKey is given, return only for this key
// mixed ArraySearchRecursive(mixed Needle,array Haystack
//                            [,NeedleKey[,bool Strict[,array Path]]])

function ArraySearchRecursive($Needle,$Haystack,$NeedleKey="",
                             $Strict=false,$Path=array()) {
  if(!is_array($Haystack))
   return false;
  foreach($Haystack as $Key => $Val) {
   if(is_array($Val)&&
       $SubPath=ArraySearchRecursive($Needle,$Val,$NeedleKey,
                                     $Strict,$Path)) {
     $Path=array_merge($Path,Array($Key),$SubPath);
     return $Path;
   }
   elseif((!$Strict&&$Val==$Needle&&
           $Key==(strlen($NeedleKey)>0?$NeedleKey:$Key))||
           ($Strict&&$Val===$Needle&&
             $Key==(strlen($NeedleKey)>0?$NeedleKey:$Key))) {
     $Path[]=$Key;
     return $Path;
   }
  }
  return false;
}
?>

Remove unnecessary new lines. I had to add them because of too long lines.
26-Jul-2006 10:19
/**
 * Searches haystack for needle and returns an array of the key path if it is found in the (multidimensional) array, FALSE otherwise.
 *
 * mixed array_searchRecursive ( mixed needle, array haystack [, bool strict[, array path]] )
 */

function array_searchRecursive( $needle, $haystack, $strict=false, $path=array() )
{
   if( !is_array($haystack) ) {
       return false;
   }

   foreach( $haystack as $key => $val ) {
       if( is_array($val) && $subPath = array_searchRecursive($needle, $val, $strict, $path) ) {
           $path = array_merge($path, array($key), $subPath);
           return $path;
       } elseif( (!$strict && $val == $needle) || ($strict && $val === $needle) ) {
           $path[] = $key;
           return $path;
       }
   }
   return false;
}
gullevek at gullevek dot org
19-Apr-2006 01:31
There were two previous entries for having a recursive search. The first one only searched for values, second one for values with an optional key.

But both of those stopped after they found an entry. I needed, that it searches recursive, with optional key and returns me all matches found in the array.

So I wrote this function:

needle is the value you search, haystack is the array of course, key is the optional key in the array where the needle should be. path should be never set on intial call. its an internal used variable.

It returns an array $path with the array entry 'found' where you can find all found groups. In these groups you have the array which holds the keys to find the data.

I hope this helps some of you.

<?php
   function array_search_recursive_all($needle, $haystack, $key, $path = NULL)
   {
       if (!$path['level'])
           $path['level'] = 0;
       if (!$path['work'])
           $path['work'] = array();
       if (!is_array($haystack))
           $haystack = array();

       // go through the array,
       foreach ($haystack as $_key => $_value)
       {
           // only value matches
           if (is_scalar($_value) && $_value == $needle && !$key)
           {
               $path['work'][$path['level']] = $_key;
               $path['found'][] = $path['work'];
           }
           // key and value matches
           elseif (is_scalar($_value) && $_value == $needle && $_key == $key)
           {
               $path['work'][$path['level']] = $_key;
               $path['found'][] = $path['work'];
           }
           elseif (is_array($_value))
           {
               // add position to working
               $path['work'][$path['level']] = $_key;
               // we will up a level
               $path['level'] += 1;
               // call recursive
               $path = array_search_recursive_all($needle, $_value, $key, $path);
           }
       }
       // cut all that is >= level
       array_splice($path['work'], $path['level']);
       // step back a level
       $path['level'] -= 1;
       return $path;
   }
?>

If you call it with this:

<?
   $right_side = array ('foo' => 'alpha', 'bar' => 'beta', 'delta' => 'gamma', 'gamma' => 'delta');
   $value = 'beta';
   $key = 'bar';
   $pos = array_search_recursive_all($value, $right_side, $key);
?>

You will find in $pos this data

<?
Array
(
   [level] => -1
   [work] => Array
       (
       )

   [found] => Array
       (
           [0] => Array
               (
                   [0] => bar
               )

       )

)
?>
RichGC
20-Mar-2006 09:54
To expand on previous comments, here are some examples of
where using array_search within an IF statement can go
wrong when you want to use the array key thats returned.

Take the following two arrays you wish to search:

<?php
$fruit_array = array("apple", "pear", "orange");
$fruit_array = array("a" => "apple", "b" => "pear", "c" => "orange");

if ($i = array_search("apple", $fruit_array))
//PROBLEM: the first array returns a key of 0 and IF treats it as FALSE

if (is_numeric($i = array_search("apple", $fruit_array)))
//PROBLEM: works on numeric keys of the first array but fails on the second

if ($i = is_numeric(array_search("apple", $fruit_array)))
//PROBLEM: using the above in the wrong order causes $i to always equal 1

if ($i = array_search("apple", $fruit_array) !== FALSE)
//PROBLEM: explicit with no extra brackets causes $i to always equal 1

if (($i = array_search("apple", $fruit_array)) !== FALSE)
//YES: works on both arrays returning their keys
?>
congaz at yahoo dot dk
10-Mar-2006 11:38
Search a multi-dimensional array on keys!
-------------------------------------------

I needed to search dynamically in a multi-dimen array on keys. I came up with this little neat function. It is so amazingly simple, that I actually didn't think it would work - but it does...

mixed array_searchMultiOnKeys(array, array);

<?php
function array_searchMultiOnKeys($multiArray, $searchKeysArray) {
   // Iterate through searchKeys, making $multiArray smaller and smaller.
   foreach ($searchKeysArray as $keySearch) {
       $multiArray = $multiArray[$keySearch];
       $result = $multiArray;
   }
  
   // Check $result.
   if (is_array($multiArray)) {
       // An array was found at the end of the search. Return true.
       $result = true;
   }
   else if ($result == '') {
       // There was nothing found at the end of the search. Return false.
       $result = false;
   }

   return $result;
// End of function,
}

// --- Test array_searchMultiOnKeys ---
$multiArray['webpages']['downloads']['music'] = 1;
$multiArray['webpages']['downloads']['pressmaterial'] = 5;
$multiArray['webpages']['links'] = 7;

array_searchMultiOnKeys($multiArray, array('webpages', 'links')); // returns 7.
array_searchMultiOnKeys($multiArray, array('webpages', 'downloads')); // returns true.
array_searchMultiOnKeys($multiArray, array('webpages', 'downloads', 'software')); // returns false.

?>

$multiArray / $searchKeysArray can be any size.

Happy hacking...
chappy at citromail dot hu
11-Feb-2006 04:26
If you're searching for strings and you need a case-insensetive script, there's one:

function array_lsearch($str,$array){
   $found=array();
   foreach($array as $k=>$v){
       if(strtolower($v)==strtolower($str)){
           $found[]=$v;
       }
   }
   $f=count($found);
   if($f===0)return false;elseif($f===1)return $found[0];else return $found;
}

It returns the original string, not the lower. Also good if use strtoupper().
hansen{}cointel.de
09-Feb-2006 10:26
may be good to take note of PHP's mind-boggling 'fuzzy' (vulgo "magic type-casting") comparison features not only in using the results, but also in the search, too:
<?php
$a=array("a","b",0,"c","d");
echo "a: ".array_search("a",$a);
echo "b: ".array_search("b",$a);
echo "c: ".array_search("c",$a);
echo "d: ".array_search("d",$a);
echo "0: ".array_search("0",$a);
echo "x: ".array_search("x",$a);
echo "1: ".array_search("1",$a);
?>
will result in:
a: 0, b: 1, c: 2, d: 2, 0: 2, x: 2, 1: false

as from "c" on, the first match found in $a is "0", as any string compared to an int is automatically cast to (int)0.
ludvig dot ericson at gmail dot com
09-Feb-2006 04:18
In response to the post beneath,
<?php

if ($userID = array_search($whatever, $array) !== false) {
}

?>

will also work, since it will be tested for explicitly NOT being a boolean false afterwards.
chrisAdams at 407x dot com
26-Jan-2006 05:32
This has been noted but took me a while to figure out: When the array that you are searching starts with position '0' array_search returns '0' for a match - evaluating as FALSE:

$usernameArray[0]='moe';
$usernameArray[1]='larry';
$usernameArray[2]='curly';

$username='moe';

// broken
if ($userNameArrayPosition=array_search($username, $usernameArray))
{ // even though the expression is true, will eval as false
echo 'userNameArrayPosition -'.$userNameArrayPosition;
}else{
echo 'evaluates false - userNameArrayPosition = -'.$userNameArrayPosition;
}
// will echo 'evaluates false - userNameArrayPosition = - 0'

// works
if (is_numeric($userNameArrayPosition=array_search($username, $usernameArray))
{ // will be true for all numeric values, but not bool. false
echo 'userNameArrayPosition -'.$userNameArrayPosition;
}else{
echo 'evaluates false - userNameArrayPosition = -'.$userNameArrayPosition;
}
// will echo 'userNameArrayPosition  - 0'

$username='homer';
if (is_numeric($userNameArrayPosition=array_search($username, $usernameArray))
{ // will be true for all numeric values, but not bool. false
echo 'userNameArrayPosition -'.$userNameArrayPosition;
}else{
echo 'evaluates false - userNameArrayPosition = -'.$userNameArrayPosition;
}
// will echo 'evaluates false - userNameArrayPosition =  - FALSE'
chrisAdams at 407x dot com
26-Jan-2006 04:53
This has been noted but took me a while to figure out: When the array that you are searching starts with position '0' array_search returns '0' for a match - evaluating as FALSE:

$usernameArray[0]='moe';
$usernameArray[1]='larry';
$usernameArray[2]='curly';

$username='moe';

// broken
if ($userNameArrayPosition=array_search($username, $usernameArray))
{ // even though the expression is true, will eval as false
echo 'userNameArrayPosition -'.$userNameArrayPosition;
}else{
echo 'evaluates false - userNameArrayPosition = -'.$userNameArrayPosition;
}
// will echo 'evaluates false - userNameArrayPosition = - 0'

// works
if (is_numeric($userNameArrayPosition=array_search($username, $usernameArray)==TRUE)
{ // will be true for all numeric values, but not bool. false
echo 'userNameArrayPosition -'.$userNameArrayPosition;
}else{
echo 'evaluates false - userNameArrayPosition = -'.$userNameArrayPosition;
}
// will echo 'userNameArrayPosition  - 0'

$username='homer';
if (is_numeric($userNameArrayPosition=array_search($username, $usernameArray)==TRUE)
{ // will be true for all numeric values, but not bool. false
echo 'userNameArrayPosition -'.$userNameArrayPosition;
}else{
echo 'evaluates false - userNameArrayPosition = -'.$userNameArrayPosition;
}
// will echo 'evaluates false - userNameArrayPosition =  - FALSE'
chernyshevsky at hotmail dot com
08-Jan-2006 09:53
array_search() in PHP 5 supports objects as needles whereas PHP 4 doesn't. The documentation should be updated to reflect this.
ludwig_von_rocht at yahoo dot com
24-Nov-2005 07:50
Here's a little function I wrote to find the key of the LAST occurrance of something in an array.

<?php
if(!function_exists('array_rsearch')){
   function array_rsearch($search, $array, $strict = false){
       $array = array_reverse($array, true);
       foreach($array as $key => $value){
           if($strict){
               if($value === $search)
                   return $key;
           } else {
               if(strpos($value, $search))
                   return $key;
           }
       }
       return false;
   }
}
?>
mark meves
23-Nov-2005 07:13
A quick-and-dirty array_search_all() that i used for a small
dup-checking routine. 

there are many, many ways to do something like this, not
the worst of which would be to use a relational database
for a dataset any larger than this ;)

-mark meves

<?php
/**
@return array of zero or more keys form $aHaystack whose
   values match $mScalarNeedle using a
   '==', (ie not strict) comparison
*/
function array_search_all($mScalarNeedle,$aHaystack){
   return array_keys( array_filter($aHaystack,
       create_function('$v','return $v == \''.addslashes($mScalarNeedle).'\';')
   ));
}

/*
test it:
*/
$aNicknames = array('jimmy'=>1,'james'=>1,'jim'=>1,
                   'billy'=>2,'william'=>2,'bill'=>2);
foreach(array('jim','bill') as $sName){
   echo "variations for \"$sName\" :(".
       implode(', ', array_search_all($aNicknames[$sName],$aNicknames)).
   ")\n";
}
/* outputs:
variations for "jim" are (jimmy, james, jim)
variations for "bill" are (billy, william, bill)
*/
?>
johnjc-phpdocs at publicinfo dot net
02-Nov-2005 02:37
The === and !== are not fully documented in either the Comparison Operator, Booleans type sections. They are talked about a bit more in the sections on strpos() and array_search() but those sections refer you to the section on Booleans for further information.

I am putting my contribution on === and !== in the Booleans section with pointers to it from the comment areas of other sections.

http://uk.php.net/manual/en/language.types.boolean.php
hakkierulez at nospamas dot hotmail dot nospam dot com
26-Oct-2005 09:36
If you simply want check if the search string is found, do this: (since the array number 0 evaluates as FALSE)

<?php
if (array_search($needle, $array)!== FALSE) {
   //code goes here (
}
?>
arborrow at jesuits dot net
26-Sep-2005 04:26
I stumbled across some unexpected behavior with the array_search function. With a little help from the DallasPHPUsersGroup, I was able to trace it down to an array that I had attempted to start with a zero. The zero must be enclosed on single quote marks for the search function to work.  Below are various syntaxes used to demonstrate the behavior. I hope this helps someone figure out why array_search is not working. Peace - Anthony

<?php

echo "<html><body>Let's try to search these arrays.<br><br>";

$findthis = "Assignments";

// syntax 1

$arcat1[] = 0; //comment out this line to test
//$arcat1[] = '0'; //uncomment this line to test
$arcat1[] = "Tests";
$arcat1[] = $findthis;
$arcat1[] = "Quizzes";
$arcat1[] = "Participation";
$arcat1[] = 0;

// the following search will not return the key if $arcat[] = 0;
// it will return the if $arcat[] = '0'; interestingly enough it will also work if $arcat = 1;
$keyresult = array_search ($findthis, $arcat1);
print_r($arcat1);
echo "<br>Arcat1 Key:".$keyresult."<br><br>";

//syntax 2

$arcat2 = array(0=>0, 1=>"Tests", 2=>"Quizzes", 3=>"Participation", 4=>"Assignments"); //comment out this line to test
//$arcat2 = array(0=>'0', 1=>"Tests", 2=>"Quizzes", 3=>"Participation", 4=>"Assignments"); //uncomment this line to test

// the following search will not return the key if $arcat2 = array(0=>0 ...);
// it will return the key if $arcat2 = array(0=>'0' ...);
$keyresult = array_search($findthis, $arcat2);
print_r($arcat2);
echo "<br>Arcat2 Key: ".$keyresult."<br><br>";

//syntax 3

$arcat3 = array(0);  //comment out this line to test
//$arcat3 = array('0'); //uncomment this line to test
array_push($arcat3, $findthis);
array_push($arcat3, "Tests");
array_push($arcat3, "Participation");
array_push($arcat3, "Quizzes");

// the following search will not return the key if $arcat3 = array(0);
// it will return the key if $arcat3 = array('0'); interestingly enough it will also work if $arcat3 = array(1);
$keyresult = array_search($findthis, $arcat3);
print_r($arcat3);
echo "<br>Arcat3 Key: ".$keyresult."<br><br>";

?>
ludvig dot ericson at gmail dot com
07-Sep-2005 03:08
To the reply below,

note that you can compare an array with another array using == and ===
05-Aug-2005 08:57
If you give a delimiter (or "glue") to implode() this because a little more robust.

To use previous example with slight modification:

$array2search = array("pat","ter","n");
$string = implode('|', $array2search); // now "pat|ter|n"

if (strpos($string, "pattern" ) !== false) {
   // wont get here
}

Now, obviously if you search for strpos($string, "pat|ter|n"), you're going to have problems again... But using a delimiter like this should help avoid most if not all "unforseen" cases.
benoit at bh-services (dot) com
19-Jun-2005 02:44
In answer to "info" at jake the spud dot com

This code doesn't work in all cases and may have unexpected results.
For example, it you have this code:

$array2search = array("pat","ter", "n");

if( strpos( implode( "", $array2search), "pattern" ) > -1 )
{
   // You will be there ... but "pattern" does not exist in the array ...
   // something is wrong !
}

There is no real solution using this code even if you try to enclose your elements by a special char ... because the special char could be part of the pattern.

If it works for you, it won't work in all cases.

/benoit
"info" at jake the spud dot com
03-Jun-2005 01:31
If you don't need the power of recursive functions, and you want to just search within an array for the existence of a string pattern, you can always try this:

if( strpos( implode( "", $array2search), "pattern" ) > -1 )
{
   // code to execute here
}

It's kind of lame and childish, but gets the job done in a pinch.

Forgive me if someone else suggested this previously. I was racking my brain trying to do this using array_search(), in_array() and the like, and all I wanted was something dead simple.
kmkz [AT] kmkz [DOT] com
07-May-2005 10:46
I always wanted an array_replace function that could search and replace within an array, so I made one (its kinda simple and a bit inefficient, but c'est la vie):

<?php

function array_replace($search, $replace, &$array) {

  foreach($array as $key => $value) {

   if($value == $search) {

     $array[$key] = $replace;

   }

  }

}

?>
vlad dot gladin at 102mg dot ro
06-Apr-2005 06:33
I found this useful especially for parsing htmls from
$file=file("http://a.website.com/htmlpage.html");

function array_search_extended($file,$str_search)
{
foreach($file as $line)
{
       if (strpos($line, $str_search)!== FALSE)
       {
             return $line;
       }
}
return false;
}
hanafi at pixella dot com
21-Jan-2005 08:37
If you want to search in a multi-dimensional array and just a portion, not the whole value, try this.

<?
$Projects[0] = array(123, "Text 1");
$Projects[1] = array(456, "Text 2");
$Projects[2] = array(789, "Text 3");

$search_value = "ext 2";

foreach ($Projects as $key => $row)
 {
     foreach($row as $cell)
     {
       if (strpos($cell, $search_value) !== FALSE)
       {
       echo  "<p>".$key;
       }
     }
 }

?>
Swoog DOT News A@T LaPoste DOT NET_DELME
18-Jan-2005 12:48
[[Excuse me but the return line of the precedent fuction had an error :( :( :( ]]

Just For Say I Had Reworked the function Object_Search in Object_Search_All :

<?php
function object_search_all(&$needle, &$haystack, $strict=false) {
   $results = array();
   if(!is_array($haystack)) return NULL;
   foreach($haystack as $k => $v) {
       if(($strict && $needle===$v) || (!$strict && $needle==$v)) $results[] = $k;
   }
 return $results == array() ? false : $results;
}
?>

it's return _NULL_ if $haystack isn't an array;
it's retrun _false_ if there is no $needle in haystack

it work also with not numerics array (thanks to a _foreach_ )

Be Happy ;) ! :D
Bye !
Swoog DOT News A@T LaPoste DOT NET_DELME
18-Jan-2005 12:29
for "voituk on asg dot kiev dot ua" :

no need to do :

(get_class($needle)==get_class($haystack[$i])) && ($needle==$haystack[$i])

for type sensible searches, Because, in PHP, two objects are equals if and only if they have same class and all of their attributes are the same (values).

But Because of the untyping of PHP, same attributes can be == but not === so, to avoid problems with type sensible searches, do :

$needle===$haystack[$i]

Is Better ! ;)
stew at initiative dot uk dot com(stewart boutcher)
05-Jan-2005 11:54
Not to labour the point too much, but here's another, slightly less verbose multi dimensional recursive function...

function array_key_exists_recursive($needle,$haystack) {

foreach($haystack as $key=>$val) {
   if(is_array($val)) { if(array_key_exists_recursive($needle,$val)) return 1; }
   elseif($val == $needle) return 1;
  }
  return 0;
}
pornsak at neowin dot net
21-Nov-2004 11:28
This is a modified version of Mark Meves's wonderful function. I needed something that would be able to let me force search the key name where the needle should be found.

<?php
function array_search_recursive($needle, $haystack, $key_lookin="") {

$path = NULL;

   if (!empty($key_lookin) && array_key_exists($key_lookin, $haystack) && $needle === $haystack[$key_lookin]) {
   $path[] = $key_lookin;

   } else {

       foreach($haystack as $key => $val) {
           if (is_scalar($val) && $val === $needle && empty($key_lookin)) {
           $path[] = $key;
           break;
           }       

           elseif (is_array($val) && $path = array_search_recursive($needle, $val, $key_lookin)) {
           array_unshift($path, $key);
           break;
           }
       }
   }

return $path;
}
?>
scripts at webfire dot org
04-Nov-2004 01:13
* Multi-Dimensional Array Search *
If you're searching for a function to search in Multi-Arrays,
this is probably usefull for you.
-------------------------------------------------------------

<?php
function multi_array_search($search_value, $the_array)
{
   if (is_array($the_array))
   {
       foreach ($the_array as $key => $value)
       {
           $result = multi_array_search($search_value, $value);
           if (is_array($result))
           {
               $return = $result;
               array_unshift($return, $key);
               return $return;
           }
           elseif ($result == true)
           {
               $return[] = $key;
               return $return;
           }
       }
       return false;
   }
   else
   {
       if ($search_value == $the_array)
       {
           return true;
       }
       else return false;
   }
}
?>

-------------------------------------------------------------
It will return an Array with the keys from the original array
where your search-string was found or false. e.g.:
-------------------------------------------------------------

<?php
$foo[1]['a']['xx'] = 'bar 1';
$foo[1]['b']['xx'] = 'bar 2';
$foo[2]['a']['bb'] = 'bar 3';
$foo[2]['a']['yy'] = 'bar 4';
$foo['info'][1] = 'bar 5';

$result = multi_array_search('bar 3', $foo);
print_r($result);
?>

-------------------------------------------------------------

Output:

Array
(
     [0] => 2
     [1] => a
     [2] => bb
)

-------------------------------------------------------------

I hope you like it ;)
greetz Udo
Flix Cloutier <felixcca at yahoo dot ca>
22-Oct-2004 08:01
There is no function to count the occurences of needle in haystack, so I made my own one...

<?php
function array_match($needle, $haystack)
{
   if( !is_array($haystack) ) return false;
  
   $i = 0;
   while( (in_array( $needle, $haystack )) != FALSE )
   {
       $i++;
       $haystack[array_search($needle, $haystack)] = md5($needle);
       reset($haystack);
   }
  
   return $i;
}
?>

I know it's a bit crappy, but don't ask me too much, I'm still only 13... ;)
voituk on asg dot kiev dot ua
29-Sep-2004 08:04
There is no way to use this function to search an object in the array.
I want to suggest my own function for this problem solve
<?php
/** $Id$
* Searches the array for a given object and returns the corresponding key if successful or FALSE otherwise
*/
function object_search($needle, $haystack, $strict=false) {
 if (!is_array($haystack)) return false;
 for ($i=0; $i<count($haystack); ++$i) {
   if ($strict) {
   // STRICT
   if ((get_class($needle)==get_class($haystack[$i])) && ($needle==$haystack[$i])) return $i;
   } else {
   // NO STRICT
   if ($needle==$haystack[$i]) return $i;
   }
 }
 return false;
}// function object_search
?>
leaetherstrip ATNOSPAM inbox DOT ru
28-Sep-2004 09:07
For get dennis dot decoene 's binary_search working on arrays with 1 or 2 elements, just replace
<?php
   while ($high - $low > 1){
?>

with

<?
   while ($high - $low >= 1){
?>
Wouter van Vliet <me at woutervanvliet dot nl>
19-Aug-2004 11:55
I was looking for a way to use a user defined function for array_search and eventually came up writing my own. Which was remarkably simple :P. Let me share this:

<?php
function array_usearch($cb, $ndl, $hs, $strict=false) {
   if (!is_array($hs)) user_error('Third argument to array_usearch is expected to be an array, '.gettype($hs).' given', E_USER_ERROR);
   foreach($hs as $key=>$value) if (call_user_func_array($cb, Array($ndl, $value, $key, $strict))) return $key;
};
?>

I'm not sure if I'm following correct conventions to specify the callback as the first argument, but it seemed most logical to me to not interrupt the order of the other four arguments (mixed needle, array haystack, boole strict).

[so far for my first post to the php notes]
andrey at php dot net
08-Aug-2004 07:56
array_search() has kind of hidden behaviour which comes from the way PHP compares values of different types (PHP is a type-loose language) - so called type juggling.
for example :
<?php
$a=array(0,0,5,0,0);
var_dump(array_search(true, $a));
?>
In the array there are only integers but we give a boolean value TRUE for be the needle. The result is that array_search() returns the first non-negative value in the haystack array. The same way if we pass FALSE it will return the first value that compared with FALSE gives TRUE - for example NULL
<?php
$a=array(1,NULL,5,0,0);
var_dump(array_search(FALSE, $a));
?>
Returns:
int(1)  <-- the key of the NULL value
softexpert [at] libertysurf [dot] fr
04-May-2004 02:51
I use this for searching for a value in a bidimensional array .

<?php
function SearchBiDimArray(&$theArray, $dimNo, $searchValue, $returnIndex = true){
   if(is_array($theArray)){
       $keys = array_keys($theArray[0]);
       $key = $keys[$dimNo];
       $elcount = count($theArray);

       for($i=0; $i < $elcount; $i++){
           if($theArray[$i][$key] === $searchValue){
               if ($returnIndex){
                   return $i;
               }
               else{
                   return $theArray[$i];
               }
           }
       }

   }
   else{
       return array_search($searchValue, $theArray);
   }
}

$theArray = array();
$theArray[0]['firstproperty'] = 'avalue1';
$theArray[0]['secondproperty'] = 'anothervalue1';

$theArray[1]['firstproperty'] = 'avalue2';
$theArray[1]['secondproperty'] = 'anothervalue2';

$theArray[2]['firstproperty'] = 'avalue3';
$theArray[2]['secondproperty'] = 'anothervalue3';

print SearchBiDimArray($theArray, 1, 'anothervalue2', true);
// result is 1

print SearchBiDimArray($theArray, 1, 'anothervalue2', true);
// result is
//Array
//(
//    [firstproperty] => avalue2
//    [secondproperty] => anothervalue2
//)

?>
ivan dot schmid at astalavista dot ch
29-Apr-2004 12:46
This is a simple Array-search & delete example.

============================================
<?PHP
//Array I am going to look in:
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');
if(in_array('blue', $array))
{ 
   unset($array[array_search('blue', $array)]); // $key = 0;
}
print_r($array);

/* Output:
Array
(
   [1] => red
   [2] => green
   [3] => red
)
*/
?>
============================================
Hope this helps someone.
Greetings Ivan
manicdepressive at mindless dot com
28-Apr-2004 10:49
<?php
/**
   recursively descend an arbitrarily deep multidimensional
   array, stopping at the first occurence of scalar $needle.
   return the path to $needle as an array (list) of keys
   if not found, return null.
   (will infinitely recurse on self-referential structures)
*/
function array_search_recursive( $needle, $haystack )
{
   $path = NULL;
   $keys = array_keys($haystack);
   while (!$path && (list($toss,$k)=each($keys))) {
     $v = $haystack[$k];
     if (is_scalar($v)) {
         if ($v===$needle) {
           $path = array($k);
         }
     } elseif (is_array($v)) {
         if ($path=array_search_recursive( $needle, $v )) {
           array_unshift($path,$k);
         }
     }
   }
   return $path;
}

?>

code till dawn!  -mark meves
pascal at hillrippers dot ch
09-Apr-2004 02:02
@@ apolion at loliart dot com:

a thought to your example:

the $key you get from your array_search is "0" (0 => 'blue'). And as for me, 0 ist the same as FALSE, so your

<?php
if($key == false)
?>

hast to evaluate to true.
after that, with the '===' -operand, you additionally compare the type of the variable  and your statement evaluates to false, because 0 !== false.

so everything seems to be okay for me. =)
apolion at loliart dot com
18-Mar-2004 06:46
This is a silly thing, but it can drive you crazy if you do not read the warning above.

<?php
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');

$key = array_search('blue', $array); // $key = 2;
echo $key;

if($key==FALSE){
  echo "FALSE";
}else{
  echo "TRUE";
}

?>

It will print FALSE.

Use this coding instead:

<?php
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');

$key = array_search('blue', $array); // $key = 2;
//$key = array_search('red', $array);  // $key = 1;
echo $key;

if($key===FALSE){
  echo "FALSE";
}else{
  echo "TRUE";
}

?>

It will return TRUE
bitmore.co.kr
18-Feb-2004 10:54
Look Print

<?php
//original
//dennis dot decoene at removthis dot moveit dot be
//18-Jan-2004 12:41

   function binsearch( $needle, $haystack ) {
       $high = count($haystack);
       $low = 0;

       while ($high - $low > 1){
           $probe = ($high + $low) / 2;
           if ($haystack[$probe] < $needle) $low = $probe;
           else $high = $probe;
       print "high = $high,low = $low,probe = $probe,\$haystack[\$probe] = $haystack[$probe] <br>";
       }

       if ($high == count($haystack) || $haystack[$high] != $needle) return false;
       else return $high;
   }
//orginal

//Look bug
   $arr=array(1,3,5,7,9,10,11,13);
   $searchfor = 0;
   print_r( binsearch($searchfor, $arr) );

   //Print Show
   //1 0    0  .
   // integer 1 or 0 bug Show look show
   //high = 4,low = 0,probe = 4,$haystack[$probe] = 9
   //high = 2,low = 0,probe = 2,$haystack[$probe] = 5
   //high = 1,low = 0,probe = 1,$haystack[$probe] = 3

   $searchfor = 1;
   print_r( binsearch($searchfor, $arr) );

   //Print Show
   // integer 1 or 0 bug Show look show
   //high = 4,low = 0,probe = 4,$haystack[$probe] = 9
   //high = 2,low = 0,probe = 2,$haystack[$probe] = 5
   //high = 1,low = 0,probe = 1,$haystack[$probe] = 3

   $searchfor = 1;
   print_r( binsearch($searchfor, $arr) );
//Print Show
//integer 3
//high = 4,low = 0,probe = 4,$haystack[$probe] = 9
//high = 2,low = 0,probe = 2,$haystack[$probe] = 5
//high = 1,low = 0,probe = 1,$haystack[$probe] = 3
//return 1
?>
dcsoboda at oakland dot edu
28-Jan-2004 05:13
I've noticed problems with array_search() when it's handling extremely large arrays.

In one example, I had a 2000 slot array with a 128 char string in each slot, and was searching for a 128 char string within the array.

It regularly returned the wrong key. I even had it print the search string, along with the found key in the array, as a  test, and it would print obvious different strings.

The problem was alleviated when I ran gzcompress() on each array slot (and on my search string, obviously). In this case, no strings were longer than 67 bytes. It performed far faster and had no accuracy problems.
20-Jan-2004 08:41
In response to dennis dot decoene:

Just remember that binary search requires the array to be sorted.  If it's not sorted (and you don't want to call sort() on it) then a binary search is not what you are lookng for.
dennis dot decoene at removthis dot moveit dot be
18-Jan-2004 02:41
It has been said before: array_search is VERY slow. Everyone knows binary search is fast by design. Here is an implementation.

<?php
$arr=array(1,3,5,7,9,10,11,13);
$searchfor = 6;
echo binsearch($searchfor, $arr);

/**
 * @return integer
 * @param var $needle
 * @param array $haystack
 * @desc Feed a sorted array to $haystack and a value to search for to $needle.
             It will return false if not found or the index where it was found.
             This function is superfast. Try an array with 50.000 elements and search for something,
             you will be amazed.
*/
function binsearch($needle, $haystack)
{
   $high = count($haystack);
   $low = 0;
  
   while ($high - $low > 1){
       $probe = ($high + $low) / 2;
       if ($haystack[$probe] < $needle){
           $low = $probe;
       }else{
           $high = $probe;
       }
   }

   if ($high == count($haystack) || $haystack[$high] != $needle) {
       return false;
   }else {
       return $high;
   }
}
?>
mjwilco at yahoo dot com
27-Nov-2003 12:42
array_search() must match the whole value, not just a portion. To search for a portion, use:

<?php
$myarray = array("some apples", "some bannanas", "some oranges");

function array_search_bit($search, $array_in)
{
   foreach ($array_in as $key => $value)
   {
   if (strpos($value, $search) !== FALSE)
   return $key;
   }
  
   return FALSE;
}

$searchkey = array_search("oranges", $myarray); //old function, returns FALSE
$searchkey = array_search_bit("oranges", $myarray); //new function, returns 2
?>
jwhite at ytztech dot com
19-Nov-2003 10:59
Searching arrays is a very slow process.  I've tried to use as many strings as I can for where an array is called, if possible. Here's a quick test to show the (eye-popping) difference between searching for a match between strings and arrays:

<?php

  $test_string = '';
  for ($i=1; $i <= 500000; $i++) {
   $test_string .= '['.$i.']';
  }

  $test_array = array();
  for ($i=1; $i <= 5000; $i++) {
   $test_array[] = $i;
  }

  $time_str = getmicrotime();
  for ($i=1; $i <= 500000; $i++) {
   strstr($i,$test_string);
  }
  $time_str = getmicrotime() - $time_str;

  $time_array = getmicrotime();
  for ($i=1; $i <= 5000; $i++) {
   array_search($i,$test_array);
  }
  $time_array = getmicrotime() - $time_array;

  echo "<H1>Test Results</H1>\r\n";
  echo "<P>String Test:&nbsp; $time_str seconds.</P>\r\n";
  echo "<P>Array Test:&nbsp; $time_array seconds.</P>\r\n";

   function getmicrotime(){
     list($usec, $sec) = explode(" ",microtime());
     return ((float)$usec + (float)$sec);
   }

?>

This code block takes some time to get going (because of the number of strings to place into memory), the results, even on modest hardware are staggering.  Comparing 500000 strstr() operations to 5000 array_search() operations on a P3-800 with 512 MB of RAM got the following output:

[H1]Test Results[/H1]
[P]String Test: 3.09137701988 seconds.[/P]
[P]Array Test:  4.23609495163 seconds.[/P]

The getmicrotime() function came from the note on microtime(), so that's not mine...credit to "daniel141 at yahoo dot com".

STRINGS RULE!
--
Justin White
YTZ Technical Services, LLC
php at celerondude dot com
12-Nov-2003 07:07
I think array_search uses serial search because they binary search function i wrote here seems to do a better job for records that are not always at the beginning of the array.

Here it is

<?php
function binarySearch ( $a, $t, $l, $r )
{
   if($t<$a[$l]||$t>$a[$r])return NULL;
   while ( $l < $r )
   {
       $m=intval($l+$r)/2;
       if($a[$m]==$t)return $m;
       elseif($t<$a[$m])$r=$m-1;
       elseif($t>$a[$m])$l = $m + 1;
   }
   if($t==$a[$r])
   return $r;
   return NULL;
}
?>

usage:
binarySearch ( array, target, left range, right range );

if your array is a multidimensional array, simply change the comparison method. :)
jcatchpoole at netbeans dot org
01-Aug-2003 01:55
The warning above about the return value being NULL for versions prior to PHP 4.2.0 actually goes for 4.2.1 also - ie 4.2.1 appears to be returning NULL rather than FALSE on failure for me.
cue at openxbox dot com
10-Jun-2003 10:50
If you are using the result of array_search in a condition statement, make sure you use the === operator instead of == to test whether or not it found a match.  Otherwise, searching through an array with numeric indicies will result in index 0 always getting evaluated as false/null.  This nuance cost me a lot of time and sanity, so I hope this helps someone.  In case you don't know what I'm talking about, here's an example:

<?php
$code = array("a", "b", "a", "c", "a", "b", "b"); // infamous abacabb mortal kombat code :-P

// this is WRONG
while (($key = array_search("a", $code)) != NULL)
{
 // infinite loop, regardless of the unset
 unset($code[$key]);
}

// this is _RIGHT_
while (($key = array_search("a", $code)) !== NULL)
{
 // loop will terminate
 unset($code[$key]);
}
?>
nospam at nowhere dot net
21-Apr-2003 10:40
array_search won't accept objects as needle (see http://bugs.php.net/bug.php?id=20681) - a possible workaround is sth. like that:

<?php
function _array_search ($needle, $haystick) {

   foreach($haystick as $key => $val) {

       if ($needle === $val) {
           return($key);
       }

   }

   return(false);
?>

}

If you require 'bool strict' add e.g. ($strict) ? $needle === $val : $needle == $val
richard at richard-sumilang dot com
16-Apr-2003 06:59
<?php
/**
     *    Search an array recursivly
     *
     *    This function will search an array recursivly
     *    till it finds what it is looking for. An array
     *    within an array within an array within array
     *    is all good :-)
     *
     *    @author        Richard Sumilang    <richard@richard-sumilang.com>
     *    @param        string    $needle        What are you searching for?
     *    @param        array    $haystack    What you want to search in
     *    @return        boolean
     *    @access        public
     */
   function array_search_r($needle, $haystack){
       foreach($haystack as $value){
           if(is_array($value))
               $match=array_search_r($needle, $value);
           if($value==$needle)
               $match=1;
           if($match)
               return 1;
       }
       return 0;
   }
?>
Darkvie
16-Mar-2003 08:53
I wanted to search a  multidimensional array for a value & assign another element of array CONTAINING the searched value.

In the array I am using ($Projects), each item in $Projects contains a "Text_ID" & "Text_Value" field from a database result. I want to search for a "Text_ID" value (456 in this example)  & get it's "Text_Value" value assigned to a variable called $Text_Value.

Here's how I did it:
============================================

<?PHP
//Array I am going to look in:
$Projects[0] = array(123, "Text 1"); 
$Projects[1] = array(456, "Text 2"); 
$Projects[2] = array(789, "Text 3"); 

// This loop goes through every element in $Projects
foreach ($Projects as $key => $ArrayRow)
{   
// Now: $ArrayRow[0] = $Projects[x][0] and $ArrayRow[1] = $Projects[x][1]

// Look for the value "456".  Assign to variable & stop looking if found.
if ($ArrayRow[0] == "456")  {$Text_Value= $ArrayRow[1]; break; }
}
?>

============================================
Hope this helps someone.
-Darkive
retestro_REMOVE at SPAM_esperanto dot org dot il
01-Mar-2003 12:46
If you're interested in finding a line in a file, after you read it into an array using file(), you can not use array_search since the match should be exact, and lines have line-endings ('\n', '\r' or '\n\r') - or else you know for sure what your lines contain physically.

The solution is to traverse the whole array, trim() each entry and then use array_search() - or - use something like the following small function I wrote for myself:

<?php
function search_array($needle, $haystack)
{
       if (!is_array($haystack) || !is_string($needle))
               return false;  // not valid argument types

       @reset($haystack);

       while (list ($key, $value) = each($haystack)) {
               $value = trim($value);  // remove spaces from the beginning and the end
               if ($value === $needle)
                       return $key;  // $needle was found, return the key
       }

       return false;  // no $needle was found in $haystack
}
?>

-----------------------------
Notes:
1. you should check the return value with === since 0 as a key equals to 'false'.
   i.e. if (search_array('my_line', $my_array) === false)  { ... }
2. I have no need in whitespace at the beginning of the line, therefore I use trim(). If it's important to you, use rtrim() or chop() instead.

-
- Sergey.
Fspillner at web dot de
14-Feb-2003 12:13
If you wanna find a value in multidimensional array with array_search. You should do the following:

Use For-Each, that it solves your Problem!

Example:

$map = array( array( Name=>'Jordan' ),
                   array( Name=>'Oneal' )
                 );

<?php
$search_value = "Jordan";

foreach ($map as $key => $row)
{
     foreach($row as $cell)
     {
         if ($cell == $search_value)
               print $key;
     }
}
?>
ryan at wonko dot com
12-Oct-2002 05:27
If you'd rather search for values in an array that match a regular expression, this function will do the trick (note that it returns the first index matched, not the last key matched as array_search does):

<?php
/**
  * Searches for a regex match in every value of a one-dimensional array.
  *
  * @param string $pattern POSIX-extended regular expression to match.
  * @param array $haystack Array to search in.
  * @return mixed Index of the first match, or FALSE if no match is found.
  */
function array_ereg($pattern, $haystack)
{
   for($i = 0; $i < count($haystack); $i++)
   {
       if (ereg($pattern, $haystack[$i]))
           return $i
   }

   return false;
}
?>
csaba at alum.mit.edu
05-Aug-2002 03:52
The following function I created should have 15 lines of code from the first if to the last return (lines 1-2,6,8-12 start with if).
Csaba Gabor

<?php
function InsertPt ($ar, $val, $searchType=0, $startPos=0, $endPos=null) {
   // Finds the position where $val should be array_spliced into
   // subarray $ar[$startPos ... $endPos] to maintain the
   // sortedness of $ar (which entire array is assumed either
   // ascending or descending).
   // This position is unique unless $val equals an $ar element:
   //
   // In this case the insertion point is such that
   // insertion of $val would happen between the first
   // encountered $val in the subarray and the element
   // just prior to that, where the search is STARTING from
   // the smallest (!$searchType is true) or
   // largest (!!$searchType is true) side of the array
   //
   // $startPos, $endPos are restricted to
   // [-sizeof($ar),sizeof($ar)-1] and are interchangeable
   // UNLESS all elements are identical in which case it
   // establishes the ascending order.  If $ar is a singleton,
   // it is assumed ascending.
   // $endPos defaults to the end of the array
   // (0 if $startPos is negative, and
   // [the normal case] sizeof($ar)-1 otherwise).
   // Negative position values should be subtracted from
   // sizeof($ar) to get absolute position.
   // Logarithmic speed.  Works with strings.
   // Adaptable to case insensitive strings (7 comparisons)

   // Examples with $ar = array(2, 4, 5, 5, 5, 6, 7, 10, 12)
   //    InsertPt ($ar, 8)          => 7
   //    InsertPt ($ar, 5)          => 2  before first 5
   //    InsertPt ($ar, 5, 1)        => 5  after the last 5
   //    InsertPt ($ar, -3)          => 0  before the 2
   //    InsertPt ($ar, 12, 1)      => 9  after the 12
   // If $ar was reversed, the same five
   // functions calls would produce 2, 7, 4, 9, 0
   // If $ar = [6, 6, 6, 6, 6]
   //    InsertPt ($ar, 8)          => 5
   //    InsertPt ($ar, 6, 1, -1, 2) => 2   
   //      that -1 translates to 4, which implies descending order

   if (!$ar || $startPos<-($aSize=sizeof($ar)) || $startPos>$aSize-1) return 0;
   if ($endPos===null) $endPos = 0 - ($startPos>=0);                        // default $endPos adjustment
   $startPos = mod(min($aSize-1, (max (-$aSize, $startPos))),$aSize);                // translate to real start pos
   $endPos =  mod(min($aSize-1, (max (-$aSize, $endPos))),  $aSize);                // translate to real end pos
   $diff = $endPos-$startPos;
   if (!($dir = ($ar[0]==$ar[$aSize-1] ? 0 : ($ar[$aSize-1]<$ar[0] ? 1 : -1))))        // constant series (-1 for ascending, 1 for descending)
   return (($val<$ar[0] || ($val==$ar[0] && !$searchType)) ? $startPos + ($diff<0) : $endPos + !($diff<0));
   if ($diff<0) { $startPos+=$endPos; $endPos=$startPos-$endPos; $startPos-=$endPos; }        // make sure $startPos <= $endPos
   if ($val<$ar[($dir<0 ? $startPos : $endPos)]) return ($dir<0 ? $startPos : $endPos+1);    // These 2 lines for when $val falls outside
   if ($val>$ar[($dir<0 ? $endPos : $startPos)]) return ($dir<0 ? $endPos+1 : $startPos);      //      series speced by $startPos, $endPos
   if ($val==$ar[($tmp=(($dir<0)==!$searchType)) ? $startPos : $endPos]) return ($tmp ? $startPos : $endPos+1);    // if $val at sensitive endpoint
   if (abs($diff)==1) return $endPos;                                // Double series (singleton was covered in 3 prior lines)
   $mid = floor(($endPos+$startPos)/2);                            // We will halve the series
   $tmp = ($dir<0)==(($val==$ar[$mid]) ? !$searchType : ($val<$ar[$mid]));            // Decide which half we want
   return InsertPt ($ar, $val, $searchType, $tmp ? $startPos : $mid, $tmp ? $mid : $endPos);   
}

function mod($num, $base) {
   // returns $num modulo $base within range [0..$base-1]
   return ($num - $base*floor($num/$base));
}
?>
saltymeat at hotmail dot com
25-Jun-2002 05:03
Here's how you can use array_search() to replace all occurances of a value in an array:

<?php
function array_replace($a, $tofind, $toreplace)
{
   $i = array_search($tofind, $a);
   if ($i === false)
   {
       return $a;
   }
   else
   {
       $a[$i] = $toreplace;
       return array_replace($a, $tofind, $toreplace);
   }
}
?>

Usage:
$a = array(1,2,3);
$a = array_replace($a, 1, 4);
echo $a[0]; // Outputs 4
dakota at dir dot bg
29-May-2002 07:44
For versions later than 4.2.0, the check  isset($key) won't work properly because the function now returns false, which "isset". This change is missing in the Change Log!

So the right way to use the function is:

<?php
$key = array_search($needle, $array);
if ($key!==null&&$key!==false) {
  ...
}
?>

This example will work in both older and newer to 4.2.0 versions.

P.S.: My previous post where isset() is used won't work in newer versions.
phil at limbrey dot net
23-May-2002 01:52
The function posted by 'chen.avinadav@vbulletin.com' on '13-Apr-2002 04:15' is wrong!

You are matching the value not the key.  It should read:

<?php
function array_search($needle, $haystack) {
   $match = false;
   foreach ($haystack as $key => $value) {
       if ($value == $needle) {
           $match = $key;
       }
   }
   return $match;
}
?>
swbrown at ucsd dot edu
02-May-2002 04:18
Be absolutely sure to check that your code that uses array_search now checks for 'false' too if you upgrade to PHP 4.2.0!

I was using array_search in my page authentication routines and this change had the fun side-effect of causing my code to always think a user had full permissions!  It was letting anyone click through to our installation of phpMyAdmin.  Not good indeed!
moz at the-allens dot net
17-Apr-2002 10:29
To future proof against the 4.2.0 return change something like this should work:

<?php
       $key = array_search($needle, $haystack);
       if(is_null($key))
           $retval = false;
?>

and then test using:

<?php
       if($key !== false)
       {
               // $key exists in $haystack.
       }
?>
admin_espace at algomas dot fr
29-Mar-2002 04:52
array search returns _a_ key not the first key. From my tests (linux-apache-php 4.1.2) it returns the last (though this may not be reliable).
i.e. the following all output 7
 print_r(array_search(1,array(0,1,1,1,1,1,6,1,8,9),true));
 print_r(array_search(1,array(0,1,2,3,4,5,6,1,8,9),true));
 print_r(array_search(1,array(1,0,2,3,4,5,6,1,8,9),true));
radley25 at earthlink dot net
10-Feb-2002 02:40
Note to the previous post:

<?php
$map = array( 'version'    => 4
           , 'OS'        => 'Linux'
           , 'lang'      => 'english'
           , 'short_tags' => true
           );
  $key = array_search("4",$map);
           print $key;
//returns short_tags
//strange results..

$array = array (1,13, 20);
 $key = array_search("13",$array);
print $key;
//works as expected
//returns 1
?>

If you put the number in quotes it searches for the array number.  Try it without the quotes.
saconner at iastate dot edu
05-Feb-2002 05:16
In PHP versions before 4.2.0 needle was not allowed to be an array.  (funnily enough, at time of posting this note, we're still at ver 4.1.1 )
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