How To Search A PHP Multidimensional Array By Value?

Implementing a Custom Search Function

To search a multidimensional array in PHP, you can create a function that loops through the array. This function will compare the 'uid' value of each sub-array with the search parameter. When it finds a match, it returns the key of the matching sub-array.

Here's how you can implement this search function:

function searchForId($id, $array) {
   foreach ($array as $key => $val) {
       if ($val['uid'] === $id) {
           return $key;
       }
   }
   return null;
}

This function takes two parameters: the ID to search for and the array to search in. It uses a foreach loop to go through each element of the array. When it finds a match, it returns the key. If it doesn't find a match, it returns null.

function searchForId($id, $array) {
    $ids = array_column($array, 'uid');
    $key = array_search($id, $ids);
    return $key !== false ? $key : null;
}

Example Implementation

Here's a complete example of how to use this search function:

// Define the sample multidimensional array
$userdb = array(
    array(
        'uid' => '100',
        'name' => 'Sandra Shush',
        'pic_square' => 'urlof100'
    ),
    array(
        'uid' => '5465',
        'name' => 'Stefanie Mcmohn',
        'pic_square' => 'urlof100'
    ),
    array(
        'uid' => '40489',
        'name' => 'Michael',
        'pic_square' => 'urlof40489'
    )
);

// Write the search function
function searchForId($id, $array) {
   foreach ($array as $key => $val) {
       if ($val['uid'] === $id) {
           return $key;
       }
   }
   return null;
}

// Demonstrate how to call the function
$result = searchForId('100', $userdb);
echo "The key for uid '100' is: " . $result;

$result = searchForId('40489', $userdb);
echo "\nThe key for uid '40489' is: " . $result;

In this example, we first define our sample multidimensional array. Then, we implement the searchForId function. Last, we show how to call the function with different 'uid' values and display the results.

This method provides a simple way to search a PHP multidimensional array by value. It's easy to understand and use, making it a good choice for many situations.

Using array_column() and array_search()

PHP has functions that can make searching multidimensional arrays easier. Two useful functions are array_column() and array_search().

array_column() takes a column from a multidimensional array. It needs three inputs: the array, the column key to extract, and an optional index key. We can use it to get all 'uid' values from the userdb array:

$uids = array_column($userdb, 'uid');

array_search() looks for a value in an array and returns the key of the first match. It needs two inputs: the value to find and the array to search. We can use it to find the key of a specific 'uid' in our extracted array:

$key = array_search('100', $uids);

By using these two functions together, we can create an efficient search method:

function searchForId($id, $array) {
    $uids = array_column($array, 'uid');
    $key = array_search($id, $uids);
    return $key !== false ? $key : null;
}

This method is often faster than looping through the array, especially for larger datasets.

$uids = array_column($userdb, null, 'uid');
$result = isset($uids['100']) ? $uids['100'] : null;

One-line Solution for PHP 5.5.0 and Later

For PHP versions 5.5.0 and later, we can write this solution in one line:

$key = array_search('100', array_column($userdb, 'uid'));

This short code combines array_column() and array_search() in one statement. It's brief and works well.

This method is fast because it doesn't manually go through the array. PHP's built-in functions are made to be quick, making this approach good for large arrays. For very small arrays, the speed difference might be small, and the loop method could work just as well.

When using this one-line solution, remember that array_search() returns false if it doesn't find the value. You might want to check for this:

$key = array_search('100', array_column($userdb, 'uid'));
$result = $key !== false ? $key : null;

This makes sure your function returns null when it doesn't find a match, staying consistent with the loop-based approach.