PHP Syntax For Dereferencing Function Result

PHP syntax for dereferencing function result

This is specifically array dereferencing, which is currently unsupported in php5.3 but should be possible in the next release, 5.4. Object dereferencing is on the other hand possible in current php releases. I'm also looking forward to this functionality!

Why can't I reference keys in the result of this PHP function?

This is only available in PHP 5.4. It is known as array dereferencing. Prior to 5.4 you have to store the return value and then access the array elements.

Docs

PHP 5.4.0 offers a wide range of new features:

• Function array dereferencing has been added, e.g. foo()[0].

If you try this on any version below 5.4, you will get this error:

Parse error: syntax error, unexpected '[' on line ...

Function call dereferencing

This is covered in this RFC by nikic. Hope they'll get it implemented sometime soon.

How does the Array dereferencing work on a scalar value of type boolean/integer/float/string as of PHP version 7.2.0?

They are referring to non-complex types such as int or float.

In your example you are using an array. So you don't see the issue.

<?php
function getArray() {
    return array(1, 2222, 3);
}
$secondElement = getArray()[1]; // 2222

$null = $secondElement[123456]; // 123456 can be any number or string
var_dump($null);

// similarly:
$also_null = getArray()[1][45678];
var_dump($also_null);

The first pair of brackets is array-dereferencing on the array (1, 2222, 3), the second is array-dereferencing on an integer (2222) which always returns null.

Simplified:

<?php
$a = 123456;
var_dump($a[42]); // is null
$a = 123.45;
var_dump($a[42]); // is null
$a = true;
var_dump($a[42]); // is null
$a = null;
var_dump($a[42]); // is null

This "fails silently" as in theory you should get an error from this, rather than just null.

Also happens with null, other than int, float, bool:

<?php 
$a = true;
var_dump($a[42][42][42][42][42][42][42][42]); // also null, and no errors

But works correctly instead with arrays and strings.

<?php
$a = "abc";
var_dump($a[1]); // b
$a = [11, 22, 33];
var_dump($a[1]); // 22

Answering your question, "How does the “Array dereferencing” work on a scalar value of type": It doesn't, it just returns null instead of returning an error of some sort.

In PHP are recalls to any given function the variable they return or a call to the function itself

In PHP version >= 5.4.0 it will not result in error, but will echo p_hello. You can check it here, changing the version number:

http://sandbox.onlinephpfunctions.com/code/db319c296ea4eb9500b9fa16bccd8f927c733d14

It is called Function Array Dereferencing:

https://wiki.php.net/rfc/functionarraydereferencing

PHP use function return value as array

PHP does not support the function array dereferencing, which you want to do.

See an RFC on the subject http://wiki.php.net/rfc/functionarraydereferencing, and the associated mailing list conversations, which was declined roughly this time last year. While there was support for this, and it's still a common request (usually "why doesn't this work?"), there are no plans in motion to introduce this syntax.

As for why, quite simply the code implementing it has not been submitted for approval (if it has been written at all).

Update

This feature has been implemented in the trunk (main development) branch of PHP and will likely be included in the next non-bugfix version (5.4.0). For anyone wanting to play with FAD, feel free to download a trunk snapshot.

mysqli_fetch_row - using it as an array - PHP

Because mysqli_fetch_row is a function that returns a value - it's not an array itself.

Assigning a variable will retrieve the result. Unfortunately that's how it works in earlier versions of PHP.

Gerald's link identifies the functionality it as availble in PHP 5.4, so I guess that you're using an earlier version.

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