This program (https://go.dev/play/p/w-QE790dGcs)
func main() {
f := 0.999
fmt.Printf("%0.2f %0.3f %0.4f\n", f, f, f)
fmt.Println(f)
fmt.Printf("%0.64f\n", f)
}
prints
1.00 0.999 0.9990
0.999
0.9989999999999999991118215802998747676610946655273437500000000000
The last line prints enough places so that it can show the actual value
stored in f. Note that this is _not_ 0.999; it is the closest approximation
that can be stored in a float64.
The first line prints the best possible approximation to this value (not to
0.999) that can be done with 2, 3, or 4 decimal places.
The middle line prints a value that, when converted to float64, will yield
the actual value stored in f. Of course, by construction of this program,
0.999 will do and is shorter than printing the actual value.
On Mon, Oct 10, 2022 at 5:40 PM Dante Castagnoli <dante.castagn...@gmail.com>
wrote:
> Sean,
>
> Your comment is not correct. You can take the original program I wrote
> and increase the digits and will notice they are printed as they are meant
> to be.
>
> Also, if you were to take an int(f), you will note that it returns "0",
> and not "1".
>
> Sorry! Incorrect information ought to be corrected. Run some tests to
> convince yourself.
>
> D
>
> On Mon, Oct 10, 2022 at 5:34 PM Sean Liao <s...@liao.dev> wrote:
>
>> > leaving one with the impression those digits will be as they are in the
>> float, and not rounded.
>>
>> This is a fundamental misunderstanding of what a float is. The rounding
>> happens the moment a value is stored in a float. The printed value is
>> exactly what is stored.
>>
>> - sean
>>
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