Help dealing with int conversions from C++ to PHP

[98InTheHole]

bradgrafelman;10998924 wrote:

Apologies for the double post, but the above post seemed long enough.

As an example of this: try executing the following code and tell us what it outputs:

function int32( $int )
{
  return( ( ( int )$int ) & 0xFFFFFFFF );
}

$number = ( int )13283415586

echo "Before: "; var_dump( $number )
echo "After:  "; var_dump( int32( $number ) );

I agree with you, that c++ code is BAD :-)

Anyway, I ran the code you sent, here's the results:

Before: int(13283415586)
After: int(398513698)

As you suspected, I am indeed running a 64bit system.

I tried using that "int32" function on $n_3, and also during the calculation, like this:

$n_3 = int32(((int32((int32(($n_1 * $n_2)) * ($n_4 + 29))) + $n_4 + 6) / ($n_1)) * $n_1);

The result was close (missed it by 1), however it's not there, I plugged in other samples I have, and I'm not getting the right result.

What else can I try?

[bradgrafelman]

98InTheHole;10998935 wrote:

I plugged in other samples I have, and I'm not getting the right result.

Can you show us an example?

[98InTheHole]

bradgrafelman;10998936 wrote:

Can you show us an example?

Sure, I can produce these numbers as I please, so I can give you as many as you want :-)

Here you go:

n1: 426
n2: 7960
n4: 4035

expected n3: 8480

n1: 671
n2: 2262
n4: 9235

expected n3: 2805

n1: 767
n2: 2642
n4: 3957

expected n3: 1971

Let me know if you want a few more.

Thanks.

[Derokorian]

Try this out =D

<?php
/* C++ code
	int n_1,n_2,n_3,n_4;

n_1 = 947;
n_2 = 1842;
n_4 = 7609;

n_3 = ((((n_1 * n_2) * (n_4 + 6)) + n_4 + 29) / (n_1)) * n_1;		

    while (n_3 > 9999)
	n_3 -= 8888;
while (n_3 < 1000)
	n_3 += 1237;
 */

$tests = array(
	2443 => array(947,1842,7609),
	8480 => array(426,7960,4035),
	2805 => array(671,2262,9235),
	1971 => array(767,2642,3957)
);

echo '<pre>';
foreach( $tests as $expected => $test ) {
	$actual = InTheHole($test[0],$test[1],$test[2]);
	echo "Expected to get: $expected\nActually got: $actual\n\n";
}
echo '</pre>';

function InTheHole($n1,$n2,$n4) {
	$part1 = (int) $n1 * $n2;
	$part2 = (int) $n4 + 6;
	$part3 = (int) $part1 * $part2;
	$part4 = (int) $n4 + 29;
	$part5 = (int) $part3 + $part4;
	$n3 = (int) $part5 / $n1;
	$n3 = (int) $n3 * $n1;
	while( $n3 > 9999 )
		$n3 -= 8888;
	while( $n3 < 1000 )
		$n3 += 1237;
	return $n3;
}

Which produces this output:

Expected to get: 2443
Actually got: 2443

Expected to get: 8480
Actually got: 8480

Expected to get: 2805
Actually got: 2805

Expected to get: 1971
Actually got: 1971

[bradgrafelman]

Derokorian;10998939 wrote:

Which produces this output:

Expected to get: 2443
Actually got: 2443

Expected to get: 8480
Actually got: 8480

Expected to get: 2805
Actually got: 2805

Expected to get: 1971
Actually got: 1971

... on a 32-bit system only. 😉

[Derokorian]

bradgrafelman;10998940 wrote:

... on a 32-bit system only. 😉

Aww damn I didn't realize I had 32bit PHP on my 64bit Win7 ha. I failed =\

[bradgrafelman]

I haven't had time to look into the past couple of responses to this thread in depth (probably won't until later this evening), but...

@: Could you execute Derkorian's test code and let us know if you get different results?

[98InTheHole]

Derokorian;10998939 wrote:

Try this out =D

<?php
/* C++ code
	int n_1,n_2,n_3,n_4;

n_1 = 947;
n_2 = 1842;
n_4 = 7609;

n_3 = ((((n_1 * n_2) * (n_4 + 6)) + n_4 + 29) / (n_1)) * n_1;		

    while (n_3 > 9999)
	n_3 -= 8888;
while (n_3 < 1000)
	n_3 += 1237;
 */

$tests = array(
	2443 => array(947,1842,7609),
	8480 => array(426,7960,4035),
	2805 => array(671,2262,9235),
	1971 => array(767,2642,3957)
);

echo '<pre>';
foreach( $tests as $expected => $test ) {
	$actual = InTheHole($test[0],$test[1],$test[2]);
	echo "Expected to get: $expected\nActually got: $actual\n\n";
}
echo '</pre>';

function InTheHole($n1,$n2,$n4) {
	$part1 = (int) $n1 * $n2;
	$part2 = (int) $n4 + 6;
	$part3 = (int) $part1 * $part2;
	$part4 = (int) $n4 + 29;
	$part5 = (int) $part3 + $part4;
	$n3 = (int) $part5 / $n1;
	$n3 = (int) $n3 * $n1;
	while( $n3 > 9999 )
		$n3 -= 8888;
	while( $n3 < 1000 )
		$n3 += 1237;
	return $n3;
}

Which produces this output:

Expected to get: 2443
Actually got: 2443

Expected to get: 8480
Actually got: 8480

Expected to get: 2805
Actually got: 2805

Expected to get: 1971
Actually got: 1971

Thanks for this, however these are NOT the results I'm getting, could it be again the 32bit vs 64bit issue?

These are my results:

Expected to get: 2443
Actually got: 6282

Expected to get: 8480
Actually got: 3618

Expected to get: 2805
Actually got: 6413

Expected to get: 1971
Actually got: 1221

What's going on? :-)

[Derokorian]

Hmm this is very confusing. Brad I hope you can clear this up but if I change the function I made to this:

function InTheHole($n1,$n2,$n4) {
	$part1 = int32($n1 * $n2);
	$part2 = int32($n4 + 6);
	$part3 = int32($part1 * $part2);
	$part4 = int32($n4 + 29);
	$part5 = int32($part3 + $part4);
	$n3 = int32($part5 / $n1);
	$n3 = int32($n3 * $n1);
	while( $n3 > 9999 )
		$n3 = int32($n3-8888);
	while( $n3 < 1000 )
		$n3 = int32($n3+1237);
	return $n3;
}
function int32( $int ) { 
  return( ( ( int )$int ) & 0xFFFFFFFF ); 
}

I get 3/4 answers correct. And the last one is WAY off:

Expected to get: 2443
Actually got: 2443

Expected to get: 8480
Actually got: 8480

Expected to get: 2805
Actually got: 2805

Expected to get: 1971
Actually got: 8526

This is on a real 64bit system (my webhost not my local machine) where I got the same output as 98InTheHole before changing it.

[bradgrafelman]

98InTheHole;10998948 wrote:

could it be again the 32bit vs 64bit issue?

Most likely yes - that'd be my first guess.

Speaking of the 64bit issue, I'd like to get a clear idea of the target environment you're dealing with. Can you do a [man]phpinfo/man in that environment and copy-paste the 'System' and 'Configure Command' items from the table at the top (they should be the first and third table rows at the very top of the page)?

Derokorian;10998951 wrote:

Brad I hope you can clear this up

Me, too, because I do feel like I missed a vital step along the way of imitating the 32-bit calculation (especially based on the latest results).

However, I'm still swamped with work, so I won't be able to figure out where I goofed until later this evening.

[98InTheHole]

bradgrafelman;10998953 wrote:

Most likely yes - that'd be my first guess.

Speaking of the 64bit issue, I'd like to get a clear idea of the target environment you're dealing with. Can you do a [man]phpinfo/man in that environment and copy-paste the 'System' and 'Configure Command' items from the table at the top (they should be the first and third table rows at the very top of the page)?

Me, too, because I do feel like I missed a vital step along the way of imitating the 32-bit calculation (especially based on the latest results).

However, I'm still swamped with work, so I won't be able to figure out where I goofed until later this evening.

Here's the info you requested, hope it helps. (I have to leave for the day, I'll be able to check your response tomorrow in case I can help with anything else)
Thanks again for looking into this.

System Linux php5-n294.wc2.dfw1.stabletransit.com 2.6.32.39-grsec-3.mosso5.1.x86_64 #1 SMP Mon May 16 20:37:28 CDT 2011 x86_64

Build Date Nov 11 2010 12:52:02

Configure Command './configure' '--build=x86_64-redhat-linux-gnu' '--host=x86_64-redhat-linux-gnu' '--target=x86_64-redhat-linux-gnu' '--program-prefix=' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib64' '--libexecdir=/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/usr/com' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--cache-file=../config.cache' '--with-libdir=lib64' '--with-config-file-path=/etc' '--with-config-file-scan-dir=/etc/php.d' '--disable-debug' '--with-pic' '--disable-rpath' '--without-pear' '--with-bz2' '--with-exec-dir=/usr/bin' '--with-freetype-dir=/usr' '--with-png-dir=/usr' '--with-xpm-dir=/usr' '--enable-gd-native-ttf' '--without-gdbm' '--with-gettext' '--with-gmp' '--with-iconv' '--with-jpeg-dir=/usr' '--with-openssl' '--with-pcre-regex=/usr' '--with-zlib' '--with-layout=GNU' '--enable-exif' '--enable-ftp' '--enable-magic-quotes' '--enable-sockets' '--enable-sysvsem' '--enable-sysvshm' '--enable-sysvmsg' '--with-kerberos' '--enable-ucd-snmp-hack' '--enable-shmop' '--enable-calendar' '--with-mime-magic=/usr/share/file/magic.mime' '--with-libxml-dir=/usr' '--enable-xml' '--with-system-tzdata' '--with-apxs2=/usr/sbin/apxs' '--without-mysql' '--without-gd' '--without-unixODBC' '--disable-dom' '--disable-dba' '--without-unixODBC' '--disable-pdo' '--disable-xmlreader' '--disable-xmlwriter' '--disable-json' '--without-pspell' '--disable-wddx' '--without-curl' '--disable-posix' '--disable-sysvmsg' '--disable-sysvshm' '--disable-sysvsem'

[johanafm]

int is signed. Thus you are dealing with max of (0111 1111 1111 1111) and min of (1111 1111 1111 1111) rathern than max of (1111 1111 1111 1111) and min of 0.

Wouldn't something like this do?

# Handle calcs with 32 bit signed ints
class Int32
{
	const MIN = -2147483648;
	const MAX = 2147483647;

public static function to32($val)
{
	$val = (int) $val;
	if ($val > self::MAX)
	{
		$val = $val & self::MAX;
	}
	elseif ($val < self::MIN)
	{
		$val = $val & self::MIN;
	}

	return $val;
}

public static function ad($lh, $rh)
{
	return self::to32($lh + $rh);
}
public static function su($lh, $rh)
{
	return self::to32($lh + $rh);
}
public static function mu($lh, $rh)
{
	return self::to32($lh * $rh);
}
public static function di($lh, $rh)
{
	return self::to32($lh / $rh);
}
}


# Test data and actual calculations
$nums = array
(
	/* 8480 */
	array
	(
		1 => 426,
		2 => 7960,
		4 => 4035
	),
	/* 2805 */
	array
	(
		1 => 671,
		2 => 2262,
		4 => 9235
	),
	/* 1971 */
	array
	(
		1 => 767,
		2 => 2642,
		4 => 3957
	)
);


foreach ($nums as $n)
{
	$n3 = Int32::mu(Int32::di(Int32::ad(Int32::ad(Int32::mu(Int32::mu($n[1], $n[2]),Int32::ad($n[4], 6)),$n[4]),29),$n[1]),$n[1]);

while ($n3 > 9999)
	$n3 -= 8888;
while ($n3 < 1000)
	$n3 += 1237; 

echo $n3 . PHP_EOL . PHP_EOL;
}

[bradgrafelman]

johanafm;10999004 wrote:

int is signed.

... and there it is. Completely overlooked that in my proposed solution before. Oops.

[Derokorian]

Johanafm running your code, for the last test I actually get 8118 on my 64bit system not 1971, however it does return correctly on 32bit (who woulda thunk). When I tried to use your class in the code I posted (instead of Brad's function) I got all wrong answers heh, so I must have tried to use it wrong. I tried like this:

function InTheHole($n1,$n2,$n4) {
	$part1 = Int32::mu($n1,$n2);
	$part2 = Int32::ad($n4,6);
	$part3 = Int32::mu($part1,$part2);
	$part4 = Int32::ad($n4,29);
	$part5 = Int32::ad($part3,$part4);
	$n3 = Int32::di($part5,$n1);
	$n3 = Int32::mu($n3,$n1);
	while( $n3 > 9999 )
		$n3 = Int32::su($n3,8888);
	while( $n3 < 1000 )
		$n3 = Int32::ad($n3,1237);
	return $n3;
}

I then got different answers on both systems. 32bit returned:

Expected to get: 2443
Actually got: 2109

Expected to get: 8480
Actually got: 1961

Expected to get: 2805
Actually got: 1234

Expected to get: 1971
Actually got: 1971

While 64bit returned:

Expected to get: 2443
Actually got: 1803

Expected to get: 8480
Actually got: 7840

Expected to get: 2805
Actually got: 2165

Expected to get: 1971
Actually got: 7478

[bradgrafelman]

@: I'm in no way advocating giving up on figuring out a portable, PHP-only solution to this... but in case you need to get this working in the near future, have you considered compiling the C code that does the calculations "correctly" (:p) and simply using PHP to call that program and capture its output?

[Derokorian]

Ok 98InTheHole are you absolutely sure the last one should be 1971 because more attempts continue to get the other answers right and continue to return 8526 for the last set of numbers.

[bradgrafelman]

@: The C++ code was provided, so you could always run the program on a 64-bit host to see the results yourself.

[Derokorian]

bradgrafelman;10999021 wrote:

@: The C++ code was provided, so you could always run the program on a 64-bit host to see the results yourself.

I have no idea how to do that. 🙁

[98InTheHole]

I really appreciate everyone's help, and I thank you all for your time.

I need to have this going by the end of the day, so I actually need to stop trying to figure it out and just find a different solution, like some of you said.

I found that the compiled version of the C++ code has a method for "spitting out" those numbers in groups of 1000, and since I only need like 10k in total for the lifetime of this project, I'm going to run it and then insert the values into a database, then use PHP simply to retrieve them instead of creating them.

Not as elegant I know, but due to the time constraints, seems like the best way out. I can always blame the C++ coder :-)

Anyway, thanks again, you guys are awesome, this is by far the best forum (in any subject) I've encountered.

[Derokorian]

This is going to bother me, so if you know you wanted to attach an SQL dump of a few hundred rows I will work on it tomorrow when I'm home bound after surgery in the morning. If not for you then for me because this has peaked my interest =D