Arrays: concatenation operator .= vs =

[StevenOliver]

Is there a subtle difference between
$array[] = 'item';
vs
$array[] .= 'item';

Thank you.

[mac_gyver]

since the $array[] syntax always appends a new element to the array, it won't contain anything to concatenate to, so, the use of the . has no meaning and is probably producing a php undefined error. what sort of error, symptom, or problem are you having that causes you to ask this?

[StevenOliver]

Thank you!!
I saw an answer on the net using $array[] .= and I had never seen the concatenation operator used with arrays (the answer had lots of upvotes, too), so I thought I'd look into it further before changing my own code :-)

[Barand]

It would only make sense if the "[ ]" contained a key value.

$array = [ 'First', 'Second', 'Third'];
$array[0] .= " item";                      // now you can use the concatenation operator

echo '<pre>', print_r($array, 1), '</pre>';
 /* OUTPUTS
         Array
        (
            [0] => First item
            [1] => Second
            [2] => Third
        )
*/

However,

$array[] .= " item";        // surprisingly it works!

 

[benanamen]

Just a reminder, in PHP 7 with strict_types, the second parameter of print_r MUST be a boolean and not an integer or it will fail with a fatal error.

Correct

<?php declare(strict_types=1); 
echo '<pre>', print_r($array, true), '</pre>';  

Fails Fatal Error

<?php declare(strict_types=1); 
echo '<pre>', print_r($array, 1), '</pre>';  

Fatal error: Uncaught TypeError: print_r() expects parameter 2 to be boolean, integer given
TypeError: print_r() expects parameter 2 to be boolean, integer given 

 

Quote

surprisingly it works!

It does "work" but it will give you an Undefined variable notice. It doesn't matter if it is an array or not.

[Barand]

Does anyone else find it ironic that you can't

declare(strict_types=true);

 

[requinix]

47 minutes ago, Barand said:

Does anyone else find it ironic that you can't

declare(strict_types=true);

 

According to Andrea (the original author of the scalar type hints RFC where strict_types came from),

Quote

I originally had it be a boolean, but considering how often this would be used, I changed it to 1 for terseness. Using 1 is common for INI settings, so I don’t think it’d be that confusing,

Shrug.

[Barand]

14 minutes ago, requinix said:

but considering how often this would be used

... or how little?

[requinix]

18 minutes ago, Barand said:

... or how little?

Either you use it everywhere or you don't use it at all. I'm in the latter camp: I like the automatic conversions, and I'm already aware of and careful with value types.

I would probably opt-in if I could do it globally, but there were good reasons not to support that and to only make it per-file.

[benanamen]

5 hours ago, Barand said:

Does anyone else find it ironic that you can't

declare(strict_types=true);

 

Well..., if that isn't a "how about that" LOL. I get the explanation by Andrea, but still.......