Why is php handling for different than foreach?

Question

I made an array $brands inside class Cars, the print_r output looks like this:

Array ( [0] => Array (  [id] => 1 
                        [name] => 'Porsche'
                    ) 
        [1] => Array (  [id] => 2 
                        [name] => 'Bugatti'
                    ) 
        [2] => Array (  [id] => 3 
                        [name] => 'BMW'
                    ) 
    )

But when I'd like to link to a certain brand, I don't want to use strtolower() to make a lowercased hyperlink. I would like to echo $cars->brands[$i]['url'] (instead of strtolower($cars->brands[$i]['name'])).

class Cars {

So I needed to create a for loop, to create the ['url'] key in the array. I thought that a foreach would work:

foreach ($this->brands as $brand => $row) {
    $row['url'] = strtolower($row['name']);
}

But it didn't. Even this did not work: $row['name'] = strtolower($row['name']);.

But this worked, though:

for ($i = 0; $i < count($this->brands); $i++) { 
    $this->brands[$i]['url'] = strtolower($this->brands[$i]['name']);
}

}

My question here is: how? why?

That's because in your `foreach`-loop, `$row` is actually a _copy_ of the original while in the `for`-loop, your accessing the actual array. — M. Eriksson, Mar 30 '17 at 11:25
@MagnusEriksson has the right of it. `foreach($this->brands as &$row)` would work. — Niet the Dark Absol, Mar 30 '17 at 11:27
You can read this post for an in-depth explanation on how `foreach` works: http://stackoverflow.com/questions/10057671/how-does-php-foreach-actually-work — M. Eriksson, Mar 30 '17 at 11:29
The concerned concept and solution are also explained in the [docs on `foreach`](http://php.net/manual/en/control-structures.foreach.php) — trincot, Mar 30 '17 at 11:30

score 4 · Answer 1 · answered Mar 30 '17 at 11:29

You need to work on a reference. Insert a & and it will work

foreach ($this->brands as $brand => &$row) {
    $row['url'] = strtolower($row['name']);
}

or you could work on the original array like:

foreach ($this->brands as $brand => $row) {
    $this->brands[$brand]['url'] = strtolower($row['name']);
}

score 3 · Accepted Answer · answered Mar 30 '17 at 11:29

3

if you want to edit the element being iterated you can add a & before $row

foreach ($this->brands as $brand => &$row) {
    $row['url'] = strtolower($row['name']);
}

but this is not necessary, just access the array from the variable available outside of the foreach loop e.g $this->brands

foreach ($this->brands as $brand => $row) {
    $this->brands[$brand]['url'] = strtolower($row['name']);
}

answered Mar 30 '17 at 11:29

john Smith

17,409
11
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1

So the `&` means you refer to `$this->brand` instead of creating a new variable? – Derk Jan Speelman Mar 30 '17 at 11:37

Touheed Khan · Answer 3 · 2017-03-30T11:33:48.150

2

because you are overwriting array key('url').

$row is a local copy of $this->brands any changes to $row will not reflect on $this->brands.

change this

foreach ($this->brands as $brand => $row) {
    $row['url'] = strtolower($row['name']);
}

with this

foreach ($this->brands as $brand => $row) {
    $this->brands[$brand]['url'] = strtolower($row['name']);
}

Happy Coding.

edited Mar 30 '17 at 11:33

answered Mar 30 '17 at 11:28

Touheed Khan

2,149
16
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1

There are many ways to solve particular problem. Thanx for appreciation. Happy Coding. – Touheed Khan Apr 02 '17 at 13:16

Why is php handling for different than foreach?

class Cars {

}

3 Answers3