php Closest minor number in array

Question

I have an array, for example (it can be anything, but it's already ordered):

array(1,7, 12, 18, 25);

I need to find what number is the closest to that array.

Taking the above array:

$needle = 11;

The number in array i want to retrieve is 7. The closest number to 11 should be 12, but i dont want the closest number, i want the minor closest number, if that makes any sense.

Another examples:

• Entering 26 the retrieved number should be 25
• Entering 1 the retrieved number should be 1
• Entering 6 the retrieved number should be 1
• Entering 7 the retrieved number should be 7
• Entering 16 the retrieved number should be 12

I found a nice function, but it does only retrieve the closest number, and not the minor closest number:

function closestnumber($number, $candidates) {
 for($i = 0; $i != sizeof($candidates); $i++) {
  $results[$i][0] = abs($candidates[$i] - $number);
  $results[$i][1] = $i;
 }
 sort($results);
 $end_result['closest'] = $candidates[$results[0][1]];
 $end_result['difference'] = $results[0][0];
 return $end_result;
}

$closest = closestnumber(8,array(1,7, 12, 18, 25));
echo "Closest: ".$closest['closest']."<br>";
echo "Difference: ".$closest['difference'];

Thanks in advance.

Answer 1

$myArray = array(1,7, 12, 18, 25); 
$needle = 11; 

$resultKey = array_search(max(array_intersect(array_values($myArray),range(0,$needle))),$myArray); 
$result = $myArray[$resultKey];

EDIT

Assumes array values will always be positive integers

Simplified version

$myArray = array(1,7, 12, 18, 25); 
$needle = 11; 

$result = max(array_intersect(array_values($myArray),range(0,$needle))); 

Answer 2

This looks like homework but I'll humour you:

function closestnumber($number, $candidates) {
    $last = null;
    foreach ($candidates as $cand) {
        if ($cand < $number) {
            $last = $cand;
        } else if ($cand == $number) {
            return $number;
        } else if ($cand > $number) {
            return $last;
        }
    }
    return $last;
}