Reading the Bug report, it was mentioned if you want precision mathmatics, use BCMath
http://www.php.net/manual/en/ref.bc.php That will give you the precision you are looking for. Jason Lotito [EMAIL PROTECTED] www.NewbieNetwork.net > -----Original Message----- > From: George Whiffen [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, December 05, 2001 3:05 PM > To: [EMAIL PROTECTED] > Subject: [PHP] Is php safe for e-commerce applications? > > > What a scary day, and it just gets worse.... > > 1. A user finds their account balance is displayed > incorrectly on one of my live e-commerce sites. > > 2. I discover that "floor()" intermittently gives the wrong > answer i.e. > > print floor(10*(8.20 - 0.20)); > Answer : 79 > > print floor(10*(8.10 - 0.10)); > Answer : 80 > > (php 4.0.6 and 4.0.4.pl1 under Linux 2.2.19.) > > 3. I find this is a known "feature" with no intention of ever > being fixed. See http://bugs.php.net/bug.php?id=6220 > > print floor( (0.7 + 0.1) * 10); > Answer : 7 > > > 4. I check the php documentation that was added because of that bug > (http://www.php.net/manual/en/language.types.float.php) and > discover :- > > "never trust floating number results to the last digit and > never compare floating point numbers for equality." > > 5. I realise that the "last digit" might also be the first so > that means never trust anything except integers! > > 6. The truth really sinks in... It seems I simply cannot use > php for e-commerce applications unless I convert all money to > integers e.g. $4.32 must be handled as 432 cents, or all > arithmetic operations and comparisons have to be converted to > use bc functions. Instead of : > > if ($cost == 10.00) > you must write > if (bcomp($cost,10.00,2)) == 0) > etc.,etc. > > 7. The horror unfolds... php is just as full of geeko-trash > as C/Perl/Java and the rest of them! I will have to spend the > rest of my life worrying about types/casts/floating point > precision and all that garbage even when I'm just adding up > dollars and cents! I can't even escape to Italy and work in > Lira, they're switching to euros with decimal places too! I > should have stayed with Java, it may be rubbish but at least > it's obviously rubbish! > > > Please someone, tell me I'm wrong! > > Tell me that 0.1 + 0.7 can be 0.8 and not almost 0.8! > Tell me I don't have to check the last three years of work! > Tell me php isn't just for kids waiting to graduate/degradate > to Java! Tell me the techno-geeks haven't won! > > Hellllllpppppppp...... > > > George > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: > [EMAIL PROTECTED] To contact the list > administrators, e-mail: [EMAIL PROTECTED] > -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
