PHP - get the biggest possible integer match from an array of integers - php

Question

I have an array of integers:
$intArr = [2, 4, 8, 16];
Given an $inputInt of 8, I need the biggest integer match from that array, which should return 8 of course.
The following function needs modification:
function getBiggestMatch($intputInt) {
$intArr = [2, 4, 8, 16];
foreach($intArr as $key => $value) {
if($key < $intputInt) {
$biggestMatch = $value;
}
}
return $biggestMatch;
}
$biggestMatch = getBiggestMatch(8); // should return 8, but returns 2 now
This function will return 2, because that is the first time that $key < $intInput. The desired result needs to be 8 from $intArr.

Answer 1

This should work for you:
First of all, just to make sure, we reindex the array and sort it with array_values() and sort().
After this we loop through the array with a while loop and always check if the next key exists and the current key => element is smaller than the input $number:
Check if next element exists Check that current array value is smaller than the input
┌─────────┴───────┐ ┌─────────┴────────┐
while(isset($arr[$key+1]) && $arr[$key] < $number)
$key++; //→ Go to next key, which must exist
Now after the while loop the $key => value can point to either a value which is the same as the input or higher. Now we just check the following:
value == input ($arr[$key] == $number) => return current value (return $arr[$key];)
distance between current value to input ($arr[$key] - $number) is smaller (<) than the distance between the last value to the input ($number - $arr[$key-1]) => return current value (return $arr[$key];)
else => return last value (return $arr[$key-1];)
Code:
<?php
function getNearestMatch($number) {
$arr = array_values([2, 4, 8, 16, 23]);
sort($arr);
$key = 0;
while(isset($arr[$key+1]) && $arr[$key] < $number)
$key++;
if($arr[$key] == $number || !isset($arr[$key-1]) || $arr[$key] - $number < $number - $arr[$key-1])
return $arr[$key];
else
return $arr[$key-1];
}
//To test it we pass some values to the function
foreach([0, 2, 3, 4, 8, 12, 22, 23, 24] as $v)
echo getNearestMatch($v) . PHP_EOL;
?>
output:
2
2
2
4
8
8
23
23
23

Answer 2

Compare the $value, not the $key. This is returning 8.
<?php
function getBiggestMatch($intputInt) {
$intArr = [2, 4, 8, 16];
foreach($intArr as $key => $value) {
if($value <= $intputInt) {
$biggestMatch = $value;
}
}
return $biggestMatch;
}
echo getBiggestMatch(8); // should return 8, but returns 2 now
?>

Answer 3

You need to do double check because if your array does not have an order the last minor value will return:
function getBiggestMatch($intputInt) {
$intArr = [4, 8, 2, 16];
$maxInt = false;
foreach($intArr as $key => $value) {
if($intputInt >= $value && $maxInt < $value) $maxInt = $value;
}
return $maxInt;
}
echo getBiggestMatch(12);
ideone code
EDIT
Following the #Rizier123's recommendation, the function needs to find the max closest value (I had not understood very well the original question), this could be a possible solution:
function getBiggestMatch($intputInt) {
$intArr = [4, 8, 2, 16];
$maxInt = false;
$diference = 0;
foreach($intArr as $key => $value) {
if( $diference == 0 || ($diference > 0 && abs($intputInt - $value) < $diference) ) {
$maxInt = $value;
$diference = abs($intputInt - $value);
}
}
return $maxInt;
}
echo getBiggestMatch(15);
ideone code