Withing RH 6.2 the original object is identical to the 
one after serialize/unserialize. No bug here.

Serialise on 4.3.2 and 4.3.0 has not the same result:
4.3.2= d:1E-06;
4.3.0= d::.E-7;


<?php
echo phpversion();
$f=1.0e-6;
$s=serialize($f);
$ff=unserialize($s);
echo "\n\n$s";
?>

// Output with php-4.3.2/sapi/cli/php
4.3.2
Notice: unserialize(): Error at offset 0 of 8 bytes in - on line 5

d::.E-7;

// Output with php-4.3.0 apache 1.3.27 on RedHat
4.3.0
d:1E-06;

// Same result on RH9.0 with all php-4.3.2RCi
http://marc.theaimsgroup.com/?l=php-dev&m=105491350013813&w=2

Please correct the version error in your last message.

Sorry, you must read,
Serialise on 4.3.2 and 4.3.0 has not the same result on RH7.2:
4.3.0= d:1E-06;
4.3.2= d::.E-7;

4.3.3-dev

d:1.E-6;

<?php
echo phpversion();
$f=1.0e-6;
$s=serialize($f);
$ff=unserialize($s);
echo "\n\n$s";
phpinfo()
?>

4.3.3RC1
d::.E-7;

phpinfo()
PHP Version => 4.3.3RC1

System => Linux paris.[skipped].com 2.4.7-10 #1 Thu Sep 6 17:27:27 EDT 2001 i686
Build Date => Jun 20 2003 10:21:42
Configure Command =>  './configure' '--with-apxs=/home/apache/bin/apxs' '--with-mysql=/usr/local/mysql' '--with-system-regex' '--enable-track-vars' '--enable-memory-limits' '--with-xml' '--with-imap=/usr/local' '--enable-sysvsem' '--enable-sysvshm' '--enable-sockets' '--with-gd' '--enable-inline-optimization' '--with-curl' '--with-zlib' '--with-bz2' '--with-gettext' '--with-pcre' '--enable-cli' '--disable-cgi' '--enable-pcntl' '--enable-url-open'
Server API => Command Line Interface
Virtual Directory Support => disabled
Configuration File (php.ini) Path => /usr/local/phpcgi/lib/php.ini
PHP API => 20020918
PHP Extension => 20020429
Zend Extension => 20021010
Debug Build => no
Thread Safety => disabled
Registered PHP Streams => php, http, ftp, compress.bzip2, compress.zlib  

This program makes use of the Zend Scripting Language Engine:
Zend Engine v1.3.0, Copyright (c) 1998-2003 Zend Technologies

You broke this, iirc.

(that was for Marcus :)

This bug has been fixed in CVS.

In case this was a PHP problem, snapshots of the sources are packaged
every three hours; this change will be in the next snapshot. You can
grab the snapshot at http://snaps.php.net/.
 
In case this was a documentation problem, the fix will show up soon at
http://www.php.net/manual/.

In case this was a PHP.net website problem, the change will show
up on the PHP.net site and on the mirror sites in short time.
 
Thank you for the report, and for helping us make PHP better.

$f=1.0e-6;
$s=serialize($f);
$ff=unserialize($s);

// Output with php4-STABLE-200306301530/sapi/cli/php
4.3.3RC2-dev
Notice: unserialize(): Error at offset 0 of 9 bytes in - on line 5

d::.0E-7;
// Please compare output with 4.3.3RC1

This bug has been fixed in CVS.

In case this was a PHP problem, snapshots of the sources are packaged
every three hours; this change will be in the next snapshot. You can
grab the snapshot at http://snaps.php.net/.
 
In case this was a documentation problem, the fix will show up soon at
http://www.php.net/manual/.

In case this was a PHP.net website problem, the change will show
up on the PHP.net site and on the mirror sites in short time.
 
Thank you for the report, and for helping us make PHP better.

The output of unserialize($s); with latest CVS is
float(1.0E-6), which is the correct output.

Bug still exists:

http://snaps.php.net/php4-STABLE-200307301730.tar.bz2

---- EXPECTED OUTPUT
string(9) "d:1.0E-6;"
float(1.0E-6)
---- ACTUAL OUTPUT
Notice: unserialize(): Error at offset 0 of 9 bytes in ~/php4-STABLE-200307301730/ext/standard
/tests/serialize/bug24063.php on line 4
string(9) "d::.0E-7;"
bool(false)
---- FAILED

Test ext/standard/tests/serialize/bug24063.phpt failed
Last correct release was 4.3.0 (4.3.1 never tested).
All version after 4.3.0 have this bug
The new function spprintf was introduced. (to be analysed)

foreach(array(0.1,0.01,0.001,0.0001,0.00001,0.000001,0.0000001,0.00000001,0.000000001) as $v){
  echo "\n$v: ".serialize($v);
}

0.1: d:0.1;
0.01: d:0.01;
0.001: d:0.001;
0.0001: d:0.0001;
1E-05: d:1.0E-5;
1E-06: d::.0E-7;  // BUG
1E-07: d::.0E-8;  // BUG
1E-08: d:1.0E-8;
1E-09: d:1.0E-9;

Still works just fine for me, but that was even before any fixes were made...assigned (again) to Marcus who opened this can of worms in the first place..

This bug has been fixed in CVS.

In case this was a PHP problem, snapshots of the sources are packaged
every three hours; this change will be in the next snapshot. You can
grab the snapshot at http://snaps.php.net/.
 
In case this was a documentation problem, the fix will show up soon at
http://www.php.net/manual/.

In case this was a PHP.net website problem, the change will show
up on the PHP.net site and on the mirror sites in short time.
 
Thank you for the report, and for helping us make PHP better.