Not quite understanding the difference between "return" / "echo" when used with functions

Hi Aaron,

Im getting a better handle on the way it needs to be set out and how it loops through to count items in the array but how do I manage to get the total of the number in the array added together :s

I know you mentioned tracking the running total using $total = null; I wasnt sure how this would calculate the/ have access to the array ?

Thanks for your help ..............(again!!)

Craig Watson - No problem.

The way the $total variable and the foreach loop works is as follows:

• Inside your function, you declare a new variable, in this case $total, and assign it to some empty value (i.e. null).
• Inside the foreach loop, each iteration adds the previous value to the current value.
• When the loop terminates, you have the sum of all the numbers in your array inside $total.

Consider the function in question:

function mimic_array_sum($array) {

  $total = null;

  foreach($array as $number) {
    $total += $number;
  };

  return $total

}

When you call this function, it is going to loop through each element of the array, and on each iteration, it will add the current $number to $total. Say for example, you called it like this:

var $my_array = [1, 2, 3];

$sum = mimic_array_sum($my_array);

There are three values in the array, so the foreach loop will run three times. On the first iteration, $total is still set to null, so you basically have $total = null + 1. On the next iteration, $total contains the result of the last iteration of the loop, in this case 1, so you have $total = 1 + 2. At this point, $total is equal to 3. When the last iteration runs, you again add the current value of $total to the current $number and reassign that value to $total, which works out to be $total = 3 + 3. Once the foreach loop has finished iterating through all the elements of the array, program execution continues to the next line, which simply says return $total. The $total that is being returned here is the variable that contains the accumulated sums from the foreach loop. This is the return value of the function, and can be assigned to other variables. In this example this is the $sum = mimic_array_sum($my_array); expression. It should be pointed out that, when the function returns, it is destroyed and all of its variables with it. The consequence of this is that you can call the function as many times as you want and always get predictable results. For example:

$numbers = [1, 2, 3];

$sum_1 = mimic_array_sum($numbers);
$sum_2 = mimic_array_sum($numbers);
...
$sum_n = mimic_array_sum($numbers);

will always give you the same result. I point this out to illustrate that the $total that is declared inside the function is thrown away after the function executes, and a new variable is created when you call the function again. That is sometimes a source of confusion as well.

Hope that helps.

Hurray !!! I've Got It,

Really big thanks for helping me on that one I'm glad I not only passed the challenge but actually now hold a good understanding of the way it works and is set out!

Thanks a lot Aaron!!

Craig Watson - Glad you got it! Happy coding!