PHP: sum of keys

Using PHP, how can I get a sum of all the keys of an array?

In this example, the result should be 10.
$a = array();
$a[3]=5;
$a[6]=2;
$a[1]=8;

Open in new window

LVL 10
skijAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

zephyr_hex (Megan)DeveloperCommented:
Iterate over the array and sum the keys.

$a[3]=5;
$a[6]=2;
$a[1]=8;
$sum = 0;
foreach($a as $key => $value) {
  $sum += $key;
}
echo $sum;

Open in new window

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Julian HansenCommented:
Or you could use the array_sum and array_keys functions
echo array_sum(array_keys($a));

Open in new window

Ray PaseurCommented:
PHP array_keys() and array_sum() is the correct solution for the example.  I don't know what would happen if there were associative keys in the array.

I know of no practical design pattern that would do something like add up the numeric values of array keys -- this almost sounds like a classroom exercise.  If you're learning PHP and want some good resources, this article can help.
http://www.experts-exchange.com/articles/11769/And-by-the-way-I-am-New-to-PHP.html

<?php // demo/temp_skij.php
/**
 * http://www.experts-exchange.com/questions/28735341/PHP-sum-of-keys.html
 *
 * http://www.experts-exchange.com/articles/11769/And-by-the-way-I-am-New-to-PHP.html
 */
error_reporting(E_ALL);
echo '<pre>';

$a =
[ 3 => 5
, 6 => 2
, 1 => 8
]
;
$keys = array_keys($a);
var_dump($keys);

$sums = array_sum($keys);
var_dump($sums);

Open in new window

It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
PHP

From novice to tech pro — start learning today.