Having issue using for loop and array together

Question

PHP: Here is what I am supposed to accomplish. And below is my code. I am definitely missing something..

Write a FOR loop using an array that prints “The product of first 10 numbers is ” followed by the product of numbers 1 through 10. Here’s a hint: do NOT begin counter at 0 or else the product will be a zero!

<?php
$numbers = 0;
$numbers = range(1 , 10);
$arrlength = count($numbers);
for ($x = 1; $x <= $arrlength; $x++) {
$numbers[$x] = $numbers + $x;
}
echo "The product of first 10 numbers is $numbers.<br>";

?>

You seem to be using $numbers for two different purposes. You should have two different variables, say $numberSum and $numbers. — Patrick Q
– Patrick Q, Commented Jul 13, 2016 at 19:48
Sounds like an assignment. You wouldn't need an array for this task. If you really need an array you could use array_sum on it to calculate the sum. php.net/manual/en/function.array-sum.php — chris85
– chris85, Commented Jul 13, 2016 at 19:51
@cmorrissey I'm also confused why the result is being summed and not multiplied since the exercise asks for a product. — TheDrot
– TheDrot, Commented Jul 13, 2016 at 19:51

j08691 · Accepted Answer · 2016-07-13 19:51:23Z

4

Essentially what you're doing is creating a factorial function for a limited case. The problems with your implementation are that you seemed to re-use the $numbers variable when it should be one variable to hold the product and one for the array 1-10. The second issue is in your loop where you loop from 1-10 but what you probably really want to do is loop from 0-9 which are the array indices so that you can get the values from the array like this:

<?php
$prod = 1;
$numbers = range(1 , 10);
$arrlength = count($numbers);
for ($x = 0; $x < $arrlength; $x++) {
     $prod *= $numbers[$x];
}
echo "The product of first 10 numbers is $prod.<br>";
?>

The output of which will be:

The product of first 10 numbers is 3628800.

answered Jul 13, 2016 at 19:51

j08691

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3 Comments

Rhett Claypool Over a year ago

yes you are correct, it is product and not sum. Not sure where I got that from.

Rhett Claypool Over a year ago

If I just want to skip the array and do this:<?php $total = 1; for ($x = 0; $x <= 10; $x++) { $total *= $total[$x]; } echo "The product of first 10 numbers is $total.<br>"; ?> why am I getting a 0 instrad of 3628800?

j08691 Over a year ago

What's $total[$x] supposed to refer to if there's no array? You probably meant

<?php  $total = 1;  for ($x = 1; $x <= 10; $x++) {  	$total *= $x;  } echo "The product of first 10 numbers is $total.<br>"; ?>

Dendromaniac · Accepted Answer · 2016-07-13 19:51:42Z

0

Please note I have not tested this code, but I'm sure it should work.

<?php
  $numbers = range(1, 10);
  $product = 1;

  for ($i = 0; $i < count($numbers); $i++) {
    $product *= $numbers[$i];
  }

  echo 'The product of the first 10 numbers is ' . $product . '<br />';
?>

answered Jul 13, 2016 at 19:51

Dendromaniac

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1 Comment

Dendromaniac Over a year ago

I just noticed you want the product not the sum :/ Just fixed that.

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