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Subject: Re: [PHP-DEV] [RFC] Add pack()/unpack() support for signed integers
 with specific endianness
In-Reply-To: <CAMU7ir+4x3UPobGS3SFQ5PhoXD-oh4-Nz5B_vuqc1qDeb4QRqg@mail.gmail.com>
Date: Wed, 24 Sep 2025 15:21:44 -0700
Cc: Alexandre Daubois <alex.daubois+php@gmail.com>,
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To: PHP internals list <internals@lists.php.net>
From: andrewf@commonground.systems (Andrew F)

On Sep 24, 2025, at 00:28, Alexandre Daubois =
<alex.daubois+php@gmail.com> wrote:
> That would be an interesting addition. Given that only those 4 have
> diverged from Perl, that could be great to sync them again. Let's wait
> for other inputs to see if someone agrees with the idea before
> potentially revamping the RFC. I personally like it.

PHP's unpack() is already fundamentally divergent from Perl's in that it =
returns an associative array, and requires its format string to be =
formatted differently from the one used by pack(). For instance, in =
Perl, one can write:

    $packed =3D pack("NNN", 123, 456, 789);
    ($x, $y, $z) =3D unpack("NNN", $packed);

and have $x =3D 123, $y =3D 456, and $z =3D 789.

In PHP, however, the following code does not work as expected:

    $packed =3D pack("NNN", 123, 456, 789);
    [$x, $y, $z] =3D unpack("NNN", $packed);

Instead of returning a list of three integers, it returns an associative =
array with one key called "NN"; the other two values aren't unpacked at =
all. Instead, one must name each of the fields in the format string and =
unpack them as an associative array:

    ["x" =3D> $x, "y" =3D> $y, "z" =3D> $z] =3D unpack("Nx/Ny/Nz", =
$packed);

I'd support changes to pack() and/or unpack() to allow them to be used =
symmetrically, but that seems like a larger change than what is being =
proposed here.

-- Andrew F=