Methods for rounding the value

There are four different methods that convert a Rat value to an integer: round, ceiling, floor, and truncate.

The round method rounds the value according to the mathematical definition: the value is rounded towards the closest integer. We can see that in the following code snippet:

say 3.14.round; # 3
say 2.71.round; # 3

(Notice that the first dot separates the decimal part of the number, while the second dot is a method call.)

Negative values are also rounded so that the result is the closest integer number. We can see that in the following code snippet:

say (-3.14).round; # -3
say (-2.71).round; # -3

The truncate method just cuts the decimal part, regardless of the sign, as follows:

say 3.14.truncate; # 3
say 2.71.truncate; # 2

say (-3.14).truncate; # -3
say (-2.71).truncate; # -2

Finally, the pair of ceiling and floor methods rounds the number to the next or previous integer, as shown here:

say 3.14.ceiling; # 4
say 3.14.floor;   # 3

say (-2.71).ceiling; # -2
say (-2.71).floor;   # -3