Iteration through arrays in arrays PHP

I would create a function and pass it into array_walk_recursive

function spam_someone($value, $key)
{
    $email=$value;
    send_evil_spam($email);
 }

 array_walk_recursive($people_to_spam, 'spam_someone');

Alternatively, you could use a RecursiveIteratorIterator to iterate sequentially over a RecursiveArrayIterator. They're poorly documented, but I believe the code would look like this:

//iterate over the array using recursion as in les' answer (doesn't gain much)
$array_iter=new RecursiveArrayIterator($people_to_spam);

//Ahh, here we go, this will let us iterate over the leaves in a sequential manner
$iter_iter=new RecursiveIteratorIterator($array_iter);
foreach($iter_iter as $email)
{
    send_evil_spam($email)
}

I find these two solutions to be the cleanest and most readable. If the array is only ever going to be 3 levels deep though, I might just hard code that. If I didn't know about either of these, I would just write my own recursive function to do it (as in les' answer).

Maybe a bit more flexible solution is Recursion:

<?php

$a = array();
$a[] = array( array( "a", "b") );
$a[] = array( array( array("c", "d"), array("e", "f"), array("g", "h")));


print_arr($a);

function print_arr($obj) {
    foreach($obj as $k => $v) {
        if(is_array($v)) {
            print_arr($v);
        }else{
            echo $v ."<br />";
        }
    }
}

Useless fact: my first recursive function that doesn't have a stop condition but a go condition.

Well, what you have here is a two-element array, where each element contains a one-element array, that contains the arrays you want to iterate over.

// This gets us the two seperate arrays
foreach ($root_array as $2nd_level_array) {

  // But now, we still have one more one-element array in each...
  // we could iterate, but since there's only one element, 
  // we can just grab that element using array_pop()
  $email_address_array = array_pop($2nd_level_array)

  // now we can iterate over each of the two lists
  foreach ($email_address_array as $email_address) {

    // process email address

  }

}

The question is not too specific about how to iterate the array, and since it's a multidimensional array there are several ways to do it.

Below i outline the two ways i see would make the most sense to me.

First off i travel through the array listing items sequential.

In my second attempt i travel through the array grouping the second level items according to key.

$a = array(
    0 => array(
    0 => array(
        0 => "test0-0-0",
        1 => "test0-0-1"
    )
    ),
    1 => array(
    0 => array(
        0 => "test1-0-0",
        1 => "test1-0-1"
    )
    )
);

echo "Method 1\n";
foreach ($a as $array) {
    foreach ($array[0] as $item) {
    echo "$item\n";
    }
}
echo "Method 2\n";
$a0 = $a[0][0];
$a1 = $a[1][0];
if (count($a0) == count($a1)) {
    for ($i=0;$i<count($a0);++$i) {
    echo $a0[$i]."\n";
    echo $a1[$i]."\n";
    }
}