rounding_up

I noticed, when we parse and validate values (in particular, the int type), we use the rint method, but unfortunately it does not work according to the round rules. Although on the website https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/rint-rintf-rintl?view=msvc-170 says something else.

I tested at several OS:

Lubuntu

daria-shanina@lnv-dshanina:~/projects/test$ ./rounding_up

rint(2.00) is 2.0 | round(2.00) is 2.0 | ceil(2.00) is 2.0 | floor(2.00) is 2.0

rint(2.10) is 2.0 | round(2.10) is 2.0 | ceil(2.10) is 3.0 | floor(2.10) is 2.0

rint(2.20) is 2.0 | round(2.20) is 2.0 | ceil(2.20) is 3.0 | floor(2.20) is 2.0

rint(2.30) is 2.0 | round(2.30) is 2.0 | ceil(2.30) is 3.0 | floor(2.30) is 2.0

rint(2.40) is 2.0 | round(2.40) is 2.0 | ceil(2.40) is 3.0 | floor(2.40) is 2.0

rint(2.50) is 2.0 | round(2.50) is 3.0 | ceil(2.50) is 3.0 | floor(2.50) is 2.0

rint(2.60) is 3.0 | round(2.60) is 3.0 | ceil(2.60) is 3.0 | floor(2.60) is 2.0

rint(2.70) is 3.0 | round(2.70) is 3.0 | ceil(2.70) is 3.0 | floor(2.70) is 2.0

rint(2.80) is 3.0 | round(2.80) is 3.0 | ceil(2.80) is 3.0 | floor(2.80) is 2.0

rint(2.90) is 3.0 | round(2.90) is 3.0 | ceil(2.90) is 3.0 | floor(2.90) is 2.0

FreeBSD

daria@2ndfreebsd:~/projects/test$ ./rounding_up

rint(2.00) is 2.0 | round(2.00) is 2.0 | ceil(2.00) is 2.0 | floor(2.00) is 2.0

rint(2.10) is 2.0 | round(2.10) is 2.0 | ceil(2.10) is 3.0 | floor(2.10) is 2.0

rint(2.20) is 2.0 | round(2.20) is 2.0 | ceil(2.20) is 3.0 | floor(2.20) is 2.0

rint(2.30) is 2.0 | round(2.30) is 2.0 | ceil(2.30) is 3.0 | floor(2.30) is 2.0

rint(2.40) is 2.0 | round(2.40) is 2.0 | ceil(2.40) is 3.0 | floor(2.40) is 2.0

rint(2.50) is 2.0 | round(2.50) is 3.0 | ceil(2.50) is 3.0 | floor(2.50) is 2.0

rint(2.60) is 3.0 | round(2.60) is 3.0 | ceil(2.60) is 3.0 | floor(2.60) is 2.0

rint(2.70) is 3.0 | round(2.70) is 3.0 | ceil(2.70) is 3.0 | floor(2.70) is 2.0

rint(2.80) is 3.0 | round(2.80) is 3.0 | ceil(2.80) is 3.0 | floor(2.80) is 2.0

rint(2.90) is 3.0 | round(2.90) is 3.0 | ceil(2.90) is 3.0 | floor(2.90) is 2.0

Windows

C:\Users\Daria\projects\test>rounding_up.exe

rint(2.00) is 2.0 | round(2.00) is 2.0 | ceil(2.00) is 2.0 | floor(2.00) is 2.0

rint(2.10) is 2.0 | round(2.10) is 2.0 | ceil(2.10) is 3.0 | floor(2.10) is 2.0

rint(2.20) is 2.0 | round(2.20) is 2.0 | ceil(2.20) is 3.0 | floor(2.20) is 2.0

rint(2.30) is 2.0 | round(2.30) is 2.0 | ceil(2.30) is 3.0 | floor(2.30) is 2.0

rint(2.40) is 2.0 | round(2.40) is 2.0 | ceil(2.40) is 3.0 | floor(2.40) is 2.0

rint(2.50) is 2.0 | round(2.50) is 3.0 | ceil(2.50) is 3.0 | floor(2.50) is 2.0

rint(2.60) is 3.0 | round(2.60) is 3.0 | ceil(2.60) is 3.0 | floor(2.60) is 2.0

rint(2.70) is 3.0 | round(2.70) is 3.0 | ceil(2.70) is 3.0 | floor(2.70) is 2.0

rint(2.80) is 3.0 | round(2.80) is 3.0 | ceil(2.80) is 3.0 | floor(2.80) is 2.0

rint(2.90) is 3.0 | round(2.90) is 3.0 | ceil(2.90) is 3.0 | floor(2.90) is 2.0

As you could see in the output, the round method works according to the rules. Maybe we should use it?

Thank you for your attention!

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Best regards,

Daria Shanina