How to find out the highest array (with most items) within multiple arrays in PHP

Question

I have multiple arrays that need to be compared on how many items they contain and select the array with the highest value (= the array with the most items in it)

E.g. I have 3 arrays:

$a_arr = array( '0' => '45', '1' => '50', '2' => '100' );
$b_arr = array( '0' => 'apple' );
$c_arr = array( '0' => 'toyota', '1' => 'ferrari', );

Now I need to compare the number of items in these arrays and select the array with the highest number of items. So, the highest in these case would be $a_arr with 3 items.

How to do that the most efficient way in PHP?

Answer 1

You can use max() to determine the longest array.

$longest = max($a_arr, $b_arr, $c_arr);
// Will return the array with highest amount of items ($a_arr)

Combine it with count() to get the amount of items in the longest array.

$longest = max(count($a_arr), count($b_arr), count($c_arr));
// Will return the max number of items (3 in this case; length of $a_arr)

• user2984974: Thanks, but couldn't it be done using something simpler and without creating additinoal array?
• Oldskool: @user2984974 Just fiddled around a bit and there is, see updated answer.
• jacouh: Incredible, I shall test it.
• dialogik: It should be $longest = max(count($a_arr), count($b_arr), count($c_arr));, see here.
• Oldskool: @GottliebNotschnabel You're right, that would return the maximum amount of items in any of the arrays. Updated the answer.

Answer 2

I propose one method:

$a_arr = array( '0' => '45', '1' => '50', '2' => '100' );
$b_arr = array( '0' => 'apple' );
$c_arr = array( '0' => 'toyota', '1' => 'ferrari', );
$result = $a_arr;
$nmax = count($a_arr);
$n = count($b_arr);
if($n > $nmax)
{
 $nmax = $n;
 $result = $b_arr;
}
$n = count($c_arr);
if($n > $nmax)
{
 $nmax = $n;
 $result = $c_arr;
}
//
// compare other arrays...
//
//
// maximal elements: $nmax, $result here is the array with the maximum of items.
//

• dialogik: Laborious but all in all correct (I actually assume something like this is what the max() function does internally). +1

Answer 3

Just for fun:

array_multisort(($c=array_map('count',(compact('a_arr','b_arr','c_arr')))),SORT_DESC,$c);
echo key($c) . ' = ' . current($c);