Re: perl newbie question

this is how i would do it:

$newt = int((($temp - 32)*5/9)*100);
print $newt/100, "\n";
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Re^2: perl newbie question by WoodyWeaver (Monk) on Jan 06, 2008 at 17:09 UTC
you might want to consider rounding before you take the int. Because your denominator is pretty large, you shouldn't get any fuzz issues, but you do want to add a half to make sure you get the correct second decimal point. int EXPR Returns the integer portion of EXPR. If EXPR is omitted, uses $_. You should not use this function for rounding: one because it truncates towards 0, and two because machine representations of floating point numbers can sometimes produce counterintuitive results. For example, int(-6.725/0.025) produces -268 rather than the correct -269; that's because it's really more like -268.99999999999994315658 instead. Usually, the sprintf, printf, or the POSIX::floor and POSIX::ceil functions will serve you better than will int().	[reply]

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Re^2: perl newbie question
by WoodyWeaver (Monk) on Jan 06, 2008 at 17:09 UTC

int EXPR

Returns the integer portion of EXPR. If EXPR is omitted, uses $_. You should not use this function for rounding: one because it truncates towards 0, and two because machine representations of floating point numbers can sometimes produce counterintuitive results. For example, int(-6.725/0.025) produces -268 rather than the correct -269; that's because it's really more like -268.99999999999994315658 instead. Usually, the sprintf, printf, or the POSIX::floor and POSIX::ceil functions will serve you better than will int().

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