Using PHP to extract key from value in an array

Question

I have a PHP array that prints the following information:

Array ( 
    [0] => 23 
    [1] => 34 
    [2] => 35 
    [3] => 36 
    [4] => 37 
    [5] => 38 
    ..<snip>..
)

I have the value and would like to cross reference it with the array to return a key. For instance, if I have a variable $value = 34 I would want to run a PHP function to return the key, which in this case is 1.

To be more specific, the array is stored in variable $pages and the value is stored in variable $nextID. I tried using array_search with no luck:

How do I go about this?

No, key returns the key the current element (from the array pointer) in the array. array_search() should return the key for an element, if it's in the array. What is it returning for you? — jraede
– jraede, Commented May 7, 2013 at 21:40

Supericy · Accepted Answer · 2013-05-07 21:40:28Z

2

array_search is exactly what you're looking for. I'm not sure how you had problems with it.

$arr = [
    5,
    10,
    15,
    20
];

$value = 15;

echo array_search($value, $arr); // 2

answered May 7, 2013 at 21:40

Supericy

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1 Comment

Tasos Bitsios Over a year ago

there's also array_flip which will swap keys<-->values in the array. php.net/manual/en/function.array-flip.php Beware: keys with the same values will be overwritten by the last key/value pair!

patryk · Accepted Answer · 2013-05-07 21:49:47Z

0

You could use foreach() like that:

<?php
$arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4);

function mySearch($array, $search){
    foreach($array as $key => $value){
        if($value == $search){
            return $key;
        }
    }
}

echo mySearch($arr, 3);
?>

answered May 7, 2013 at 21:49

patryk

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1 Comment

JCHASE11 Over a year ago

for each is generally slower than array_search gist.github.com/Ocramius/1290076

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