Storing Arrays in PHP Sessions

Let's consider the code we made in the previous lesson:

html<?php
  if (!empty($_GET)) {
    $_SESSION['num1'] = $_GET['num1'];
    $_SESSION['num2'] = $_GET['num2'];
  }
?>

Actually, we could take and write all form data at once into $_SESSION:

test1.php<?php
  if (!empty($_GET)) {
    $_SESSION = $_GET;
  }
?>

And in the file test2.php do this:

test2.php<?php
  if (!empty($_SESSION)) {
    echo array_sum($_SESSION);
  }
?>

The advantage of this approach is that our code will work regardless of the number of inputs in the form.

However, there is also a drawback: by overwriting $_SESSION we erase all data that was previously there. Who knows what another script of ours wrote there? And we will delete it.

Let's do it differently:

test2.php<?php
  if (!empty($_GET)) {
    $_SESSION['nums'] = $_GET;
  }
?>

As you can see, we wrote not just one value into the session variable, but an entire array. Now in the file test2.php we can find the sum of the elements of this array:

test2.php<?php
  if (!empty($_SESSION)) {
    echo array_sum($_SESSION['nums']);
  }
?>