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
– user1597430, Commented Oct 23, 2018 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
– Pipe, Commented Oct 23, 2018 at 19:55

Don't Panic · Accepted Answer · 2018-10-23 20:12:34Z

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, 2018 at 20:12

Don't Panic

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4 Comments

JimB814 Over a year ago

I love your name! Thanks for ending my panic. It works! I found another way here

Don't Panic Over a year ago

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.)

JimB814 Over a year ago

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.

Don't Panic Over a year ago

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.

Sergey B. · Accepted Answer · 2018-10-23 19:54:08Z

<?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);
?>

Community · Accepted Answer · 2023-11-17 20:29:45Z

0

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

edited Nov 17, 2023 at 20:29

CommunityBot

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answered Oct 23, 2018 at 20:10

Shobi

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Comments

Osama · Accepted Answer · 2018-10-23 20:26:33Z

0

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

edited Oct 23, 2018 at 20:26

answered Oct 23, 2018 at 20:01

Osama

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4 Comments

Osama Over a year ago

$value from first foreach loop is array so I didn’t understand why second foreach is wrong

user1597430 Over a year ago

print_r([[], null]) is your friend here.

user1597430 Over a year ago

P.S. Now your if(count($value)>0){ solution is not a solution at all, please study print_r output first.

user1597430 Over a year ago

P.P.S. Now your if($id!=null) is not required anymore.

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