#31007 [Bgs]: intval

From: Date: Tue, 11 Jan 2005 23:39:31 +0000
Subject: #31007 [Bgs]: intval
References: 1  Groups: php.bugs 
Request: Send a blank email to php-bugs+get-71888@lists.php.net to get a copy of this message 
 ID:               31007
 Updated by:       tony2001@php.net
 Reported By:      mc at paycash dot ru
 Status:           Bogus
 Bug Type:         Math related
 Operating System: Windows 2000
 PHP Version:      5.0.2
 New Comment:

Read here about floating point limitations: 
http://www.php.net/manual/en/language.types.float.php



Previous Comments:
------------------------------------------------------------------------

[2005-01-12 00:32:02] tony2001@php.net

Floating point values have a limited precision. Hence a value might 
not have the same string representation after any processing. That also
includes writing a floating point value in your script and directly 
printing it without any mathematical operations.
 
Thank you for your interest in PHP.

Also, your reproduce code can be easily reduced to ONE string:
echo intval(100.0*40.23);
Next time plz provide a *readable* reproduce code.

------------------------------------------------------------------------

[2004-12-07 10:52:22] mc at paycash dot ru

Description:
------------
Incorrect result of intval function or combination of functions where
intval present.

Reproduce code:
---------------
/* Rounds float by tuncating any numbers after second digit since
decimal point */
function myRound($f) {
	/* Step by step trace */
	print "--Begin--\n\t\t";
	print floatval($f);													print "\n\t\t";
	print 100.0*floatval($f);										print "\n\t\t";
	print intval(100.0*floatval($f));						print "\n\t\t";	//This line
working incorrect, cause intval(4023) must be 4023 not 4022!!!!
	print intval(100.0*floatval($f))/100.0;			print "\n\t";
	print "--End--\n";
	
	return sprintf("%.2f",intval(100.0*floatval($f))/100.0);
}
//////Error appears only with this number, any other number i've tried
gave the correct result
$a=40.2396;
print "----Lets try $a\n\t";
$a=myRound($a);
print "----Returned:";print $a;print "\n\n";
print "----Lets try $a\n\t";
$a=myRound($a); //a==40.23
print "----Returned:";print $a;print "\n\n"; //a==40.22!!!!!!!!

Expected result:
----------------
----Lets try 40.2396
	--Begin--
		40.2396
		4023.96
		4023
		40.23
	--End--
----Returned:40.23

----Lets try 40.23
	--Begin--
		40.23
		4023
		4023
		40.23
	--End--
----Returned:40.23

Actual result:
--------------
----Lets try 40.2396
	--Begin--
		40.2396
		4023.96
		4023
		40.23
	--End--
----Returned:40.23

----Lets try 40.23
	--Begin--
		40.23
		4023
		4022
		40.22
	--End--
----Returned:40.22


------------------------------------------------------------------------


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