CODEWITHSUNDEEP
phparrayssorting
Ryan
Ryan

Reputation: 15270

How can I return the key of the last item in an array matching a value?

How do you recommend fetching the key of the last matching value in an array?

$arr = array(
     0 => 0,
     1 => 1,
     2 => 2,
     3 => 3,
     4 => 4,
     5 => 5,
     6 => 5,
     7 => 5,
     8 => 5,
     9 => 5, // <--- this is the key I'm after!
    10 => 6,
    11 => 7,
    12 => 8,
    13 => 9,
    14 => 10,
    15 => 11);

function returnLastMatching($haystack,$needle) {
    // return 9
}

echo returnLastMatching($arr,5);  // "9"

Upvotes: 1

Views: 913

Answers (9)

Patsy Issa
Patsy Issa

Reputation: 11293

Try the following: 

$last_key = -1;
$foreach ($haystack as $key => $value) {
    if ($value == $needle) {
        $last_key = $key;
    }
}

Each time the value = the needle it will overwrite the last element and save the key, in the end you will have the last occurrence.

== As Bora suggested ==

function returnLastMatching($haystack,$needle) {
    return array_pop(array_keys($haystack, $needle));
}

Upvotes: 2

Sara Oumina
Sara Oumina

Reputation: 52

This should probably work:

    function returnLastMatching($haystack,$needle) {
    foreach($haystack as $key=>$element)
    {



        if($element==$needle)
        {
            $temp=$key;
        }

    }
      return $temp;
    }

Upvotes: 0

Charaf JRA
Charaf JRA

Reputation: 8334

FIRST SOLUTION:

This solution using array_search() and array_reverse() , you first reverse your array and then take the first key that matchs your needle:

function returnLastMatching($haystack,$needle) {
  return   array_search($needle,array_reverse($haystack, true));
}

SECONDE SOLUTION:

Use array_keys() to get all keys that match your needle , and then get the last element from this array of keys:  

   function returnLastMatching($haystack,$needle) {

      return end(array_keys( $haystack, $needle));
  }

Upvotes: 1

david
david

Reputation: 3218

change echo returnLastMatching($arr,5); with

$arr = array_flip($arr);
echo $arr[5];

No need to use function we can get the result

Upvotes: 0

Khawer Zeshan
Khawer Zeshan

Reputation: 9646

You can use array_keys

$keys = array_keys($arr, 5); //will return all matched keys
echo end($keys); //will output the last key it was matched with

Upvotes: 1

NDM
NDM

Reputation: 6830

The foreach construct has 2 possible signatures, one of which will also give you the key value of the current element:

function returnLastMatching($haystack,$needle) {
    foreach (array_reverse($haystack) as $k => $val) 
        if ($val == $needle) return $k;
    // instead of
    // foreach ($haystack as $val)...
}

To get the last element, the array_reverse call is added while passing the array to foreach.

Upvotes: 1

Freeman Lambda
Freeman Lambda

Reputation: 3655

$lastkey = false;
foreach($haystick as $key => $val) {
    if($val === $needle) $lastkey = $key;
}
return $lastkey;

This will iterate to the end of the haystick, thus returning the last key if there is at least one, or false if there is none.

Upvotes: 1

Ivan Ivanic
Ivan Ivanic

Reputation: 3054

function returnLastMatching($haystack,$needle) {
    return array_pop(array_keys($haystack, $needle));
}

Upvotes: 1

Bora
Bora

Reputation: 10717

Try this one with array_pop and array_keys

function returnLastMatching($haystack,$needle) {
    return array_pop(array_keys($haystack, $needle));
}

Process

get keys with array_keys

array (size=5)
  0 => int 5
  1 => int 6
  2 => int 7
  3 => int 8
  4 => int 9

get last element with array_pop

9

Upvotes: 2

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