| php at richardneill dot org 2006-09-20, 7:58 am |
| ID: 38888
User updated by: php at richardneill dot org
Reported By: php at richardneill dot org
-Status: Feedback
+Status: Open
Bug Type: Documentation problem
PHP Version: Irrelevant
New Comment:
Here's why I think it matters:
1) The documentation for gmp_init explicitly states:
"String representation can be decimal or hexadecimal".
which implies "...but not octal"
2) gmp_init uses strings, not numbers. However, PHP does different
things with strings. See Code 1: I'd expect $c and $d to behave like
$b.
3) It's "common sense" that 010 means ten. I've been using PHP daily
for 5 years, and (mea culpa), I'd completely forgotten that PHP does
octal. Of course, I'd never normally write integers that way, but see
Code 2 for an example bug, which is specific to gmp, and where I
initially omitted the ltrim(,0)
I also can't see my comment - I'll re-add it.
========== Code 1 ==========
<?
$a=010;
$b="010" + 0;
$c=gmp_strval(gmp_init(010));
$d=gmp_strval(gmp_init("010"));
echo "a: $a, b: $b, c: $c, d: $d\n";
//prints a: 8, b: 10, c: 8, d: 8
//Expected: all 8, or all 10.
?>
==========================
========= Code 2 ==========
if (preg_match("/^[0-9]+\.[0-9]+$/",$input)){
//Input is a base-10 decimal.
$pieces=explode(".", $input);
//Multiply as necessary to remove the decimal point.
//Convert that to a gmp_resource, then decrement the
//exponent to compensate.
$input="$pieces[0]$pieces[1]";
//Remove the decimal point.
$input=ltrim($input,'0');
//Then remove any leading zeros. We must remove leading
//zeros, since otherwise, (and contrary to the
//documentation), gmp_init will parse the number as
//octal! Eg 0.25 becomes 025e-1 which becomes 21 * 10-1
if ($input==''){
$input=0;
//Fix the case of 0.0, or it would be ''
}
$input=gmp_init($input);
$exponent=-strlen($pieces[1]);
//Exponent is (-) the number of characters after
//the decimal point.
}
===========================
Previous Comments:
------------------------------------------------------------------------
[2006-09-20 06:44:14] bjori@php.net
What exactly gave you the impression it $i = 010; should
be 10?
IMO it is very well documented at php.net/integer and has
nothing to do GMP what so ever.
(I don't see your note anywhere..)
------------------------------------------------------------------------
[2006-09-19 23:57:22] php at richardneill dot org
Description:
------------
The documentation for gmp_init implies that a number will only be
parsed as hexadecimal if it begins with 0x, and decimal otherwise.
Thus: "10" means ten
"0x10" means sixteen
"010" means ten.
However, in practice, "010" is parsed as eight!.
Not sure whether this is a documentation bug, or an actual bug though.
Personally, I'd prefer "010" to mean ten, but I am aware of some
conventions in which it means octal.
Confusingly:
$x=010 //$x is eight
$x="010" //$x is ten
Please also correct the comment I added to the gmp_init page - I said
that it 010 was parsed as hex, when I meant octal.
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=38888&edit=1
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