Как найти индекс элемента массива php

It perfectly searches through multi-dimentional arrays combined with array_column() (min php 5.5.0) but it may not return the values you'd expect.

<?php array_search($needle, array_column($array, 'key')); ?>

Since array_column() will produce a resulting array; it won't preserve your multi-dimentional array's keys. So if you check against your keys, it will fail.

For example;

<?php
$people = array(
  2 => array(
    'name' => 'John',
    'fav_color' => 'green'
  ),
  5=> array(
    'name' => 'Samuel',
    'fav_color' => 'blue'
  )
);$found_key = array_search('blue', array_column($people, 'fav_color'));
?>

Here, you could expect that the $found_key would be "5" but it's NOT. It will be 1. Since it's the second element of the produced array by the array_column() function.

Secondly, if your array is big, I would recommend you to first assign a new variable so that it wouldn't call array_column() for each element it searches. For a better performance, you could do;

<?php
$colors = array_column($people, 'fav_color');
$found_key = array_search('blue', $colors);
?>

<?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]);

}

?>

<?php

array_search(strtolower($element),array_map('strtolower',$array));

?>

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", $fruit_array))
//PROBLEM: the first array returns a key of 0 and IF treats it as FALSEif (is_numeric($i = array_search("apple", $fruit_array)))
//PROBLEM: works on numeric keys of the first array but fails on the secondif ($i = is_numeric(array_search("apple", $fruit_array)))
//PROBLEM: using the above in the wrong order causes $i to always equal 1if ($i = array_search("apple", $fruit_array) !== FALSE)
//PROBLEM: explicit with no extra brackets causes $i to always equal 1if (($i = array_search("apple", $fruit_array)) !== FALSE)
//YES: works on both arrays returning their keys
?>

function array_recursive_search_key_map($needle, $haystack) {
    foreach($haystack as $first_level_key=>$value) {
        if ($needle === $value) {
            return array($first_level_key);
        } elseif (is_array($value)) {
            $callback = array_recursive_search_key_map($needle, $value);
            if ($callback) {
                return array_merge(array($first_level_key), $callback);
            }
        }
    }
    return false;
}

usage example:
-------------------

$nested_array = $sample_array = array(
    'a' => array(
        'one' => array ('aaa' => 'apple', 'bbb' => 'berry', 'ccc' => 'cantalope'),
        'two' => array ('ddd' => 'dog', 'eee' => 'elephant', 'fff' => 'fox')
    ),
    'b' => array(
        'three' => array ('ggg' => 'glad', 'hhh' => 'happy', 'iii' => 'insane'),
        'four' => array ('jjj' => 'jim', 'kkk' => 'kim', 'lll' => 'liam')
    ),
    'c' => array(
        'five' => array ('mmm' => 'mow', 'nnn' => 'no', 'ooo' => 'ohh'),
        'six' => array ('ppp' => 'pidgeon', 'qqq' => 'quail', 'rrr' => 'rooster')
    )
);

$search_value = 'insane';

$array_keymap = array_recursive_search_key_map($search_value, $nested_array);

var_dump($array_keymap);
// Outputs:
// array(3) {
// [0]=>
//  string(1) "b"
//  [1]=>
//  string(5) "three"
//  [2]=>
//  string(3) "iii"
//}

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

But again, with the above solution, PHP again falls short on how to dynamically access a specific element's value within the nested array. For that, I wrote a 2nd function to pull the value that was mapped above.

function array_get_nested_value($keymap, $array)
{
    $nest_depth = sizeof($keymap);
    $value = $array;
    for ($i = 0; $i < $nest_depth; $i++) {
        $value = $value[$keymap[$i]];
    }

    return $value;
}

usage example:
-------------------
echo array_get_nested_value($array_keymap, $nested_array);   // insane

<?php

var_dump

(array_search('needle', [ 0 => 0 ])); // int(0) (!)var_dump(array_search('needle', [ 0 => 0 ], true)); // bool(false)?>

But, in php 8

<?php

var_dump

(array_search('needle', [ 0 => 0 ])); // bool(false)?>

If you're searching for a string and you have a "true" boolean on the way - you will get it as result (first occurrence). Example below:

<?php

$arr

= [
    'foo'    => 'bar',
    'abc'    => 'def',
    'bool'   => true,
    'target' => 'xyz'
];var_dump( array_search( 'xyz', $arr ) ); //bool
var_dump( array_search( 'xyz', $arr, true ) ); //target?>

When searching for a string and the array contains 0 (zero), the string is casted to (int) by the type-casting which is always 0 (perhaps the opposite is the proper behaviour, the array value 0 should have been casted to string). That produces unexpected results if strict comparison is not used:

<?php
$a = array(0, "str1", "str2", "str3");
echo "
str1 = ".array_search("str1", $a).",
str2 = ".array_search("str2", $a).",
str3 = ".array_search("str3", $a).",

str1 strict = "

.array_search("str1", $a, true).",
str2 strict = ".array_search("str2", $a, true).",
str3 strict = ".array_search("str3", $a, true);
?>

This will return:
str1 = 0, str2 = 0, str3 = 0, str1 strict = 1, str2 strict = 2, str3 strict = 3

The problem is that unless you specify "strict" the match is done using ==    and in that case any string will match a numeric value of zero which is not what you want.

-----

also, php can lookup an index pretty darn fast.  for many scenarios, it is practical to maintain multiple arrays, one in which the index of the array is the search key and the normal array that contains the data.

<?php

  $normal

[$index] = array('key'=>$key, 'data'=>'foo');

  $inverse[$key] = $index;
//very fast lookup, this beats any other kind of search
if (array_key_exists($key, $inverse))

  {

    $index = $inverse[$key];

    return $normal[$index];

  }
?>

Assume you have the following array:
<?php
$arr = [
           1 => 'index 0',
           2 => 'index 1',
           3 => 'index 2',
           '3anothersuffix' => 'index 3'
];$index1 = array_search('3', array_keys($arr)); // 2
$index2 = array_search('3anothersuffix', array_keys($arr)); //2
?>

$index1 and $index2 will be the same

after using strict type search:

<?php
$index1 = array_search('3', array_keys($arr), true); // false
$index2 = array_search('3anothersuffix', array_keys($arr), true);  //3
?>

it will not find $index1 at all while returning a correct value for $index2;

<?php

$haystack

= array('a','b','a','b');$needle = 'a';print_r(array_search_all($needle, $haystack));//Output will be
// Array
// (
//         [0]=>1
//         [1]=>3
// )function array_search_all($needle, $haystack)
{#array_search_match($needle, $haystack) returns all the keys of the values that match $needle in $haystackforeach ($haystack as $k=>$v) {

            if(

$haystack[$k]==$needle){$array[] = $k;
        }
    }
    return ($array);

    }

?>

<?php
$arr = ['apple', 'banana'];var_dump($arr[0] === 'apple'); // true
var_dump($arr[false] === $arr[0]); // true
var_dump($arr[false] === 'apple'); // trueunset($arr[array_search('banana', $arr)]); //index = 1
var_dump($arr);// result
//   array(1) {
//     [0]=>
//     string(5) "apple"
//   }unset($arr[array_search('peach', $arr)]); //not found, result is false
var_dump($arr);// result
//   array(0) {
//   }
// because $arr[false] === $arr[0]
?>

So always check the return of array_search!

<?php
function array_ksearch($array, $str)
{
    $result = array();
    for($i = 0; $i < count($array); next($array), $i++)
        if(strtolower(current($array)) == strtolower($str))
            array_push($result, key($array);

        return

$result;
}
?>

Usage would be as follows:
<?php
$testArray = array('one' => 'test1', 'two' => 'test2', 'three' => 'test1', 'four' => 'test2', 'five' => 'test1');
    print_r(array_ksearch($testArray, 'test1'));
?>