Iterating over multidimensional array where some arrays might have no elements

Question

I have a $products array like this:

Array
(
    [0] => Array
        (
            [0] => 1001
            [1] => 1002
        )

    [1] => 
    [2] => 
    [3] => 
    [4] => 
    [5] => 
    [6] => 
    [7] => 
)

I want to loop through it and create a one-level array comprised only of the non-empty array data like this:

$newArr = [
    [0] => 1001,
    [1] => 1002
]

My foreach loop that I thought would work throws an error ('Invalid argument supplied for foreach()').

The foreach loop looks like this:

$idArr = [];
foreach($products as $value) {
    foreach ($value as $id) {
        echo $id . '<br>';
        $idArr[] = $id;
    }
}

The two values echo suggesting the code is correct, but it's not. I am unable to store the iterated $id value into $idArr[].

If anyone can spot my error or errors, I would appreciate it.

Thanks!

replace `$products` with `array_filter($products)` inside your `foreach`. — user1597430, Oct 23 '18 at 19:54
Some of your original array have null elements... not empty arrays... then you must use the second foreach only if `$value` is not empty... then add `if (!empty($value)) { foreach($value as $id){} }` — Pipe, Oct 23 '18 at 19:55

score 1 · Answer 1 · answered Oct 23 '18 at 20:12

1

You don't need to change your code much, you can just skip the inner loop if there's no value.

$idArr = [];
foreach($products as $value) {
    if (!$value) continue;   // continue to next iteration without executing the inner loop
    foreach ($value as $id) {
        $idArr[] = $id;
    }
}

Or enclose the inner loop in an if ($value) ... block. However you like, as long as you're not trying to iterate arrays that aren't there.

answered Oct 23 '18 at 20:12

Don't Panic

41,125
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1

I love your name! Thanks for ending my panic. It works! I found another way [here](https://stackoverflow.com/questions/20131948/php-array-merge-if-not-empty) – JimB814 Oct 23 '18 at 20:27
Thanks :-) Since that other post solves your problem, I think you can flag your own question as a duplicate of it. (I'd prefer not to do that myself since I answered and my vote will close it instantly.) – Don't Panic Oct 23 '18 at 20:31
It's subjective, but I don't think it's a duplicate. In fact, your answer is concise, and therefore, at least in my mind, superior. Brevity wins. In addition, you showed me `continue` which I never knew. Great and unique answer. – JimB814 Oct 23 '18 at 20:33
Sure, that's fine, it's up to you. Just wanted to let you know, because most people don't realize it's possible to flag their own posts. I've closed a couple of my own questions after finding good duplicate answers. Many people also view duplicate closures as a negative thing, but it's really not. Your question just becomes a pointer to an answer that already exists. – Don't Panic Oct 23 '18 at 20:39

score 0 · Answer 2 · answered Oct 23 '18 at 19:54

<?php
$arrayTest = [
        'country' => [
            'Russian Federation' => [
                'Region' => [
                    'Moscow',
                    'Moscow',
                    'Moscow'
                ],
                'Moscow', 
                'Moscow', 
                'Moscow'
            ],
            "United States of America" => [
                'Moscow', 
                'Moscow', 
                'Moscow'
            ],
            "China" => [
                'Moscow', 
                'Moscow', 
                'Moscow'
            ]
        ],

        'union' => [
            'Moscow', 
            'Moscow'
        ], 

        'status' => 1, 

        'age' => 34
    ];

$result = [];
array_walk_recursive($arrayTest, function ($item, $key) use (&$result) {
    $result[] = $item;    
});
print_r($result);
?>

Osama · Answer 3 · 2018-10-23T20:26:33.297

0

$idArr = array();
foreach($products as $value) {
    if(is_array($value)){
        foreach ($value as $id) {
                $idArr[] = $id;
         }
      }
 }

edited Oct 23 '18 at 20:26

answered Oct 23 '18 at 20:01

Osama

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$value from first foreach loop is array so I didn’t understand why second foreach is wrong – Osama Oct 23 '18 at 20:11
`print_r([[], null])` is your friend here. – user1597430 Oct 23 '18 at 20:15
P.S. Now your `if(count($value)>0){` solution is not a solution at all, please study `print_r` output first. – user1597430 Oct 23 '18 at 20:18
P.P.S. Now your `if($id!=null)` is not required anymore. – user1597430 Oct 23 '18 at 20:23

score 0 · Answer 4 · answered Oct 23 '18 at 20:10

You could use PHP Spl RecursiveIteratorIterator

$array = array(1,2,array(3,4, array(5,6,7), 8),[0=>1, 1=> [0=>null]], 9);
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($a));
foreach($it as $v) {
  echo $v, " ";
}

prints

1 2 3 4 5 6 7 8 1 9

reference modified to suit your example

Iterating over multidimensional array where some arrays might have no elements

4 Answers4