In the past (1990s) there have been banks caught skimming. They were always exchanging (with other banks) amounts of currency (fe EUR to USD) specifically chosen so the error was always in their favour.
Never Use Floats for Money (2016)
11–20 of 41 posts
Re: Never Use Floats for Money (2016)
#12the perennial stackoverflow question -> https://stackoverflow.com/questions/3730019/why-not-use-doub...
A real life example: in the R language, this statement resolves to FALSE
> 74.20+153.20==227.40
[1] FALSERe: Never Use Floats for Money (2016)
#13More time has passed between Office Space (1999) and today than between Office Space and Superman 3 (1983).
Re: Never Use Floats for Money (2016)
#14I remember hearing this back when I worked on financial software for hedge funds (2005ish), adjusting our product so it represented currencies as integer numbers of cents, taking the change to my boss (the company CEO), and then hearing "Use floats for money. All of our customers do, and if we don't you'll create needless friction for them." Ran into it more recently when doing cryptocurrency market analytics. Bitcoi…
> and then hearing "Use floats for money. All of our customers do, and if we don't you'll create needless friction for them."
Until a competent customer doesn't, then you've got to explain to them why your calculations are intentionally wrong, never a good look. Regulatory bodies also tends to want the correct decimal numbers.
Re: Never Use Floats for Money (2016)
#15I just use blobs for everything. Just in case.
Re: Never Use Floats for Money (2016)
#16Great advice on going for the lowest (cents) so you can work with integers. I do something similar with dates on all my apps where I go for ints in the database and always save unix timestamps. I can't stand dates unless I'm working with timestamps.
Same! Dates are one of the biggest sources of programmer error in my experience, and representing them as ints until they are rendered to a UI prevents a lot of it.
Re: Never Use Floats for Money (2016)
#17Great advice on going for the lowest (cents) so you can work with integers. I do something similar with dates on all my apps where I go for ints in the database and always save unix timestamps. I can't stand dates unless I'm working with timestamps.
Actually, using timestamps for all dates is a bit like using floats for currency. For many cases it doesn't matter, but you lose information.
Re: Never Use Floats for Money (2016)
#18the perennial stackoverflow question -> https://stackoverflow.com/questions/3730019/why-not-use-doub... A real life example: in the R language, this statement resolves to FALSE > 74.20+153.20==227.40 [1] FALSE
[deleted]
Re: Never Use Floats for Money (2016)
#19I remember hearing this back when I worked on financial software for hedge funds (2005ish), adjusting our product so it represented currencies as integer numbers of cents, taking the change to my boss (the company CEO), and then hearing "Use floats for money. All of our customers do, and if we don't you'll create needless friction for them." Ran into it more recently when doing cryptocurrency market analytics. Bitcoi…
[deleted]
Re: Never Use Floats for Money (2016)
#20I tried a small C++ program and it does not exhibit this behavior. Why is it not showing there?
program: #include
using namespace std;
int main(int argc, char argv) { float s = 165 * 1.40; cout output: ./floats 231