how to find key from any array php - php

Question

I have a string, I need to know at what index is that string exist in the array. My array is as follows:
array(3)
{
[0]=>object(stdClass)#47170 (3)
{
["countries"]=>string(2) "HK"
["last_seen_date"]=>string(10) "2016-09-17"
["ad_uid"]=>string(14) "157d5908a1ca83"
}
[1]=>object(stdClass)#47171 (3)
{
["countries"]=>string(2) "HK"
["last_seen_date"]=>string(10) "2016-09-27"
["ad_uid"]=>string(14) "157d7978513bc3"
}
[2]=>object(stdClass)#47230 (3)
{
["countries"]=>string(2) "HK"
["last_seen_date"]=>string(10) "2016-09-27"
["ad_uid"]=>string(14) "157ea7239824e9"
}
}
The last seen date is:2016-09-27.
I would like to know at what index does 2016-09-27 exist in the array. So I know what is ad_uid related to that date. I have a method which does this.
public function getAd_uid($last_seen_date,$values){
$key = array_keys($values,$last_seen_date);
print_r($key);
}
The result gets an empty array. I have tried array_serach() has same empty results. Any other alternative solutions to achieve results?

Answer 1

To find all $ad_uids last_seen at particular date you can use array_filter which will return you all elements you are looking for. If you need ad_uids only, you can apply array_map to that array as following:
<?php
// $array is the array in question.
$filtered = array_filter($array, function($item) {
return $item->last_seen_date == "2016-09-27";
});
$ad_uids = array_map(function($item){return $item->ad_uid;}, $filtered);
Example

Answer 2

As each each entry of your array is an object and you know the attributs' names of theses objects (I assume they never change), I would do it like this :
/**
* #param string $last_seen_date
* #param array $values
* #return mixed null|int
*/
function getAdUid($last_seen_date, array $values) {
// Just in case no entry match
$matching_index = null;
// Loop through each entry: $entry is an object
foreach($values as $index => $entry) {
if($entry->last_seen_date == $last_seen_date) {
$matching_index = $index;
break; // end loop: we found that we are looking for
}
}
return $matching_index;
}

Answer 3

to do that just loop your array
foreach($values as $key => $row) {
// do something
}
then check if $last_seen_date is equal to the loop index last_seen_date $row->last_seen_date
if ($row->last_seen_date == $last_seen_date) {
return $key;
}
if it is just return it
return $key;
so your php code would be like this
$arr = array(
0 =>
(object)array(
"countries" => "HK",
"last_seen_date" => "2016-09-17",
"ad_uid"=> "157d5908a1ca83"
),
1 =>
(object)array(
"countries" => "HK",
"last_seen_date" => "2016-09-20",
"ad_uid" => "157d7978513bc3"
),
2 =>
(object)array(
"countries" => "HK",
"last_seen_date" => "2016-09-26",
"ad_uid" => "157ea7239824e9"
)
);
function getAd_uid($last_seen_date, $values){
foreach($values as $key => $row) {
if ($row->last_seen_date == $last_seen_date) {
return $key;
}
}
}
echo '2016-09-17 is on index => '.getAd_uid('2016-09-17', $arr).'<br>';
echo '2016-09-20 is on index => '.getAd_uid('2016-09-20', $arr).'<br>';
echo '2016-09-26 is on index => '.getAd_uid('2016-09-26', $arr).'<br>';
RESULT
Working Demo