You’d be dismayed to find out how often I’ve seen people do that.
Comment on IEEE 754
tdawg@lemmy.world 2 weeks agoPlease tell me you aren’t using floating points with money
psivchaz@reddthat.com 2 weeks ago
zqwzzle@lemmy.ca 2 weeks ago
Yeah I shudder when I see floats and currency.
Womble@lemmy.world 2 weeks ago
Eh, if you use doubles and you add 0.000314 (just over 0.03 cents) to ten billion dollars you have an error of 1/1000 of a cent, and thats a deliberately perverse transaction. Its not ideal but its not the waiting disaster that using single precision is.
SubArcticTundra@lemmy.ml 2 weeks ago
That sounds like an accident waiting to happen
Saleh@feddit.org 2 weeks ago
How do you do money? Especially with stuff like some prices having three or four decimals
jmcs@discuss.tchncs.de 2 weeks ago
Instead of representing $1.102 as
1.102your store it as1012(or whatever precision you need) and divide by 1000 only for displaying it.Saleh@feddit.org 2 weeks ago
So if you handle different precisions you also need to store the precision/exponent explicitly for every value. Or would you sanitise this at input and throw an exception if someone wants more precision than the program is made for?
wewbull@feddit.uk 2 weeks ago
No exponent, or at least a common fixed exponent. The technique is called “fixed point” as opposed to “floating point”. The rationale is always to have a known level of precision.
jmcs@discuss.tchncs.de 2 weeks ago
It depends on the requirements of your app and what programming language you use. Sometimes you can get away with using a fixed precision that you can assume everywhere, but most common programming languages will have some implementation of a decimal type with variable precision if needed, so you won’t need to implement it on your own outside of university exercises.
wewbull@feddit.uk 2 weeks ago
Knowing not to use floating point with money is good use of that knowledge.