ID: 49636
User updated by: hsu at jean-david dot com
Reported By: hsu at jean-david dot com
-Status: Feedback
+Status: Closed
Bug Type: Strings related
Operating System: linux
PHP Version: 5.2.11
New Comment:
"If there were a pack format character which is exactly the size of a
PHP int, this would mean only PHP with the same int size could read it"
This is also true with the "i" format.
The reason that I use pack is to manipulate bit streams in PHP, but
yes, I would use serialize to just store an int.
You are right, there is no big inconvenience using the "l" format and
it's fixed size.
I did not know that it was a design choice not to have a format
character for a PHP int.
Yes, please mark this bug as solved.
Thank you for the explanation.
Previous Comments:
------------------------------------------------------------------------
[2009-10-01 11:35:57] sjo...@php.net
Correct. You can assume that an PHP int is always 32 bits and use l for
pack. However, pack() is probably the wrong tool for the thing you want
to do.
The pack() function is mainly useful to interoperate with other
programs or protocols. In that case, you typically know the format and
sizes of things you want to pack.
If there were a pack format character which is exactly the size of a
PHP int, this would mean only PHP with the same int size could read it.
If you want to store and retrieve data using only PHP, you are better
off using serialize().
Is this clear, and do you consider this bug solved?
------------------------------------------------------------------------
[2009-09-24 10:41:35] hsu at jean-david dot com
There is no easy way to pack a plain old php integer
This means that pack has many different format codes but none for a php
int?
------------------------------------------------------------------------
[2009-09-23 07:28:36] sjo...@php.net
Thank you for your bug report.
The integer in the pack documentation and the integer in the PHP
integer documentation refer to different things. The pack integer is a
C-style int. The PHP integer is implemented in a long. These do not need
to be the same size.
------------------------------------------------------------------------
[2009-09-23 01:54:13] hsu at jean-david dot com
Description:
------------
PHP pack documentation:
i signed integer (machine dependent size and byte order)
PHP integer documentation:
Integer size can be determined using the constant PHP_INT_SIZE
On some systems, I believe that the word "integer" will refer to
objects of different sizes, such that pack("i", _) could point to an
object of size X bytes and PHP_INT_SIZE return value Y which is
inconsistent.
/main/main.c l.1796:
REGISTER_MAIN_LONG_CONSTANT("PHP_INT_SIZE", sizeof(long),
CONST_PERSISTENT | CONST_CS);
/ext/standard/pack.c l.402-403:
php_pack(argv[currentarg++], sizeof(int), int_map,
&output[outputpos]);
outputpos += sizeof(int);
Reproduce code:
---------------
file_put_contents("test.bin",pack("I", 2));
var_dump(PHP_INT_SIZE === filesize("test.bin"));
Expected result:
----------------
bool(true)
Actual result:
--------------
bool(false)
------------------------------------------------------------------------
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Edit this bug report at http://bugs.php.net/?id=49636&edit=1
