Bug #17726: Serious comparision operator bug using floating point vars

From: Snelders@Infocure.nl Operating system: Redhat kernel 2.2.19-7.0.12 PHP version: 4.2.1 PHP Bug Type: Unknown/Other Function Bug description: Serious comparision operator bug using floating point vars --- My code --- <? $HRDelta = 1; function HRValue($Max = 100){ global $HRDelta; $C = ($Max < 0 ? -1 : 1); $Order = floor(log10($Max * $C)); $i = 1; do{ $AxisMax = $i * $HRDelta * pow(10,$Order); $i++; }while($Max * $C >= $AxisMax); echo "Expression: (\$Max * \$C >= \$AxisMax) ? \"true\" : \"false\")<BR>\n"; echo "Evaluated: (" . $Max * $C . " >= $AxisMax) ? \"true\" : \"false\")<BR>\n"; echo "Answer: " . (($Max * $C >= $AxisMax) ? "true" : "false") . "<BR>"; return $C * $AxisMax; } echo HRValue(-0.7); ?> --- My Output --- Expression: ($Max * $C >= $AxisMax) ? "true" : "false") Evaluated: (0.7 >= 0.7) ? "true" : "false") Answer: false -0.7 --- Description problem --- The last comparison operator returns false for some unknown reason. I also checked the variables using var_dump and they seem to be exactly the same (float(0.7)) according to php. --- My configure line -- './configure' '--with-apxs=/usr/sbin/apxs' '--with-mysql=/usr/' '--with-png-dir=/usr/local/libpng' '--with-gd=/usr/local/gd-1.8.4' '--with-zlib' '--with-ttf' '--with-freetype-dir=/usr/local/freetype2' '--with-xml' '--with-oracle=/users/home/oskarsson/OraHome1' '--with-oci8=/users/home/oskarsson/OraHome1' -- Edit bug report at http://bugs.php.net/?id=17726&edit=1 -- Fixed in CVS: http://bugs.php.net/fix.php?id=17726&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=17726&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=17726&r=needtrace Try newer version: http://bugs.php.net/fix.php?id=17726&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=17726&r=support Expected behavior: http://bugs.php.net/fix.php?id=17726&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=17726&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=17726&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=17726&r=globals