CODEWITHSUNDEEP
phparrays
chin
chin

Reputation: 11

Use array values as keys of another array

I have the following array:

$array1 = array("X", "Y", "Z")

The array values of $array1 are the keys of another array. And I want to access that element like this:

$array2["X"]["Y"]["Z"]

Any idea on how I would do this?

Upvotes: 0

Views: 174

Answers (2)

kamal pal
kamal pal

Reputation: 4207

You can loop through with keys array, and check whether keys are present in source array, and keep storing them to a new array.

At last when keys loop finishes, you will left with result in your new array.

$array1 = array("X","Y","Z");
$array2 = array('X' => array('Y' => array('Z' => array('A' => 'B'))));

function getValue($keys, $source){
    $ref = $source;
    foreach($keys as $key) {
        if(isset($ref[$key])) $ref = $ref[$key];
        else return false;
    }
    return $ref;
}

print_r(getValue($array1, $array2));

Example: https://eval.in/571509

Upvotes: 0

Rizier123
Rizier123

Reputation: 59681

Explanation

First off we will assign $array1 and $array2 to other variables, since we are going to modify and work with them. So in case you need the original arrays later on. We assign the first array, which are the keys of the second, to the variable $keys. And the second array to $tmp:

$keys = $array1;
$tmp = $array2;

Then we are going to loop over the keys with a while loop and always shift the first element down from the array with array_shift():

while($key = array_shift($keys)){

}

Means in my example it would be:

iteration 1: $key = A
iteration 2: $key = B
iteration 3: $key = C

As I said before we assign the second array to $tmp. This means:

$array2 = ["A" => ["B" => ["C" => "RESULT"]]];
$tmp = $array2;
//$tmp  = ["A" => ["B" => ["C" => "RESULT"]]];

Now we start the loop and check if $key exists in our $tmp variable. If it does we assign that element back to $tmp and loop over the next key and do the same. If at any point the key does not exist we can break the loop.

Visualized:

iteration 1:
    key = A
    tmp = ["A" => ["B" => ["C" => "RESULT"]]]
    
    tmp[A] = EXISTS TRUE
        TRUE  -> tmp = tmp[A] //tmp = ["B" => ["C" => "RESULT"]]
        FALSE -> break

iteration 2:
    key = B
    tmp = ["B" => ["C" => "RESULT"]]
    
    tmp[B] = EXISTS TRUE
        TRUE  -> tmp = tmp[B] //tmp = ["C" => "RESULT"]
        FALSE -> break

iteration 3:
    key = C
    tmp = ["C" => "RESULT"]
    
    tmp[C] = EXISTS TRUE
        TRUE  -> tmp = tmp[C] //tmp = "RESULT"
        FALSE -> break

tmp = "RESULT"

Now at the end we of course have to check if all those keys existed and we got our result in $tmp or not. We do this just by checking if $tmp is not an array anymore and didn't got "stuck" somewhere by a key which wasn't found.

Code

<?php

    $array1 = ["A", "B", "C"];
    $array2 = ["A" => ["B" => ["C" => "RESULT"]]];
    
    $keys = $array1;
    $tmp = $array2;
    
    while($key = array_shift($keys)){
        if(isset($tmp[$key]))
            $tmp = $tmp[$key];
        else
            break;
    }

    if(!is_array($tmp))
        echo $tmp;
    else
        echo "Element does not exist";

?>

Upvotes: 2

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