Create an array from pairwiseDifference function - php

Question

this is my code:
$arry = (10,20,30,40,50)
function pairwiseDifference($arry, $n)
{
$diff = 0;
for ($i = 0; $i < $n - 1; $i++)
{
// absolute difference between
// consecutive numbers
$diff = abs($arry[$i] - $arry[$i + 1]);
echo $diff." ";
}
}
// Driver Code
$n = sizeof($arry);
echo "<br> Percent of commisions are: "; pairwiseDifference($arry,$n); // this echo 10,10,10,10
So now i wanna make the results of pairwise funcition an array to use in another code, i tried to put:
$arru = pairwiseDifference($arry,$n)[1];
$arru1 = pairwiseDifference($arry,$n)[2];
$arru2 = pairwiseDifference($arry,$n)[3];
$arru3 = pairwiseDifference($arry,$n)[4];
echo $arru;
echo $arru1;
echo $arru2;
echo $arru3;
But are not working.
What im wrong?
Thanks in advance!

Answer 1

An array declaration in PHP needs to either have the array keyword or it can just be declared with square brackets []:
$arry = array(10,20,30,40,50);
or
$arry = [10,20,30,40,50];
You can get the size of an array with the count() method, and there is no need to pass it as a parameter to your function:
function pairwiseDifference($arry)
{
$n = count($arry);
// ...
}
Your function doesn't return anything, so the variables $arru, $arru1, ... won't get anything back from the function and will remain empty. In order to return an array of differences and solve your problem you can do this:
function pairwiseDifference($arry)
{
$n = count($arry) - 1; // you can add the -1 here
$diff = 0;
$result = array();
for ($i = 0; $i < $n; $i++)
{
// absolute difference between
// consecutive numbers
$diff = abs($arry[$i] - $arry[$i + 1]);
echo $diff." ";
array_push($result, $diff); // use array_push() to add new items to an array
}
return $result; // return the result array
}
$arry = array(10,20,30,40,50);
echo "<br> Percent of commisions are: ";
// this echos 10,10,10,10 and assigns whatever your function returns
// to the variable $diffArray
$diffArray = pairwiseDifference($arry);
$arru = $diffArray[0]; // array elements start at index 0
$arru1 = $diffArray[1];
$arru2 = $diffArray[2];
$arru3 = $diffArray[3];
echo $arru; // prints 10
echo $arru1; // prints 10
echo $arru2; // prints 10
echo $arru3; // prints 10