Comment by anonzzzies
1 year ago
I saw this so many times. It is rather depressing. Even experienced devs hardly know enough about floats, rounding etc to implement these things, but they do. We were asked to troubleshoot a project for an online insurer ; the devs did two conversions; js and php. So the amount from the frontend ended on the server and got converted and got into the db as an entry. Definitely depressing how frontend numbers are converted and actually this means something to the end result. But the php conversion was also wrong, so it was often cents off. I believe people should never be allowed to have a 'senior developer' job again, but this is really quite commonplace. Most companies don't have enough revenue to notice or care, but given how often we see it, I would say it's actually normal.
While I've never worked on financial systems myself, I was told many times that monetary amounts should always be stored and manipulated as integer amounts of smallest units of currency (cents). One reason being that integer math is always exact, while floating-point isn't. And when money is involved, you want your math to be exact so everything always adds up every step of the way. So I'm always calling it out when someone is using floats to store money.
well, you could do this, but it would make world much more complex when working with the numbers in the code - todays highlevel languages like Java or C# have a "decimal" datatype which should be used for money/accounting, these types also offer several digits of accuracy, if required.
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