Re: number comparison with a twist

I am assuming you know What Every Computer Scientist Should Know About Floating-Point Arithmetic, since you say "this fails due to the way floats are stored in memory". On the off-chance you (or a future reader) needs a refresher, I have included the link.

Since the prices are coming as floats-in-a-string, you have it easy: you should just be able to strip out the decimal point. Assuming it's always got exactly two digits following, $price_string =~ s/\.(\d{2})$/$1/;. After this, it will be in string and numeric form as integer cents. parv already posted a regex that just strips the decimal point from anywhere in the string.

Alternately, don't use the int, which does truncation; instead, use a round-to-nearest, like round of POSIX

Comment on Re: number comparison with a twist Download Code

Replies are listed 'Best First'.
Re^2: number comparison with a twist by anotherguest (Novice) on Mar 02, 2020 at 15:29 UTC
I did not at all consider this solution, unfortunately, that also means I posted a too simplified prototype. The API can return the price with variable leading and trailing digits, so `19.900000` is a valid result as is `123.2` so a bit of an extension is needed: `$price_string .= '0'; $price_string =~ s,^(\d+)\.(\d{2})0*,${1}${2},;` [download]	[reply] [d/l] [select]
Re^3: number comparison with a twist by parv (Parson) on Mar 02, 2020 at 15:42 UTC
Does that mean you may also be getting data with built-in imperfect decimal representation? Please have clear rounding rules before doing anything serious.	[reply]
Re^4: number comparison with a twist by anotherguest (Novice) on Mar 02, 2020 at 15:54 UTC
Is it possible? I guess it is. After all, I have no control over the API. Then again, the prizes I get are end prizes including VAT so they MUST always be describable in whole cents. This is also the reason the database was set up to store them as integer cents, to avoid any rounding issues (that worked very well, right?). So, truncating to 2 decimal digits is The Right Thing(TM) in this case.	[reply]
Re^5: number comparison with a twist by pryrt (Abbot) on Mar 02, 2020 at 16:10 UTC
Re^3: number comparison with a twist by LanX (Saint) on Mar 02, 2020 at 17:57 UTC
> The API can return the price with variable leading and trailing digits, so 19.900000 is a valid result as is 123.2 In this case my last reply should be perfect. :) Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply]


Do you know where your variables are?
	PerlMonks