Definition and application of sub-boundary types

Reference:

If we define an integer type, his range-2147483648 ... 2147483647, in fact, a program of variables are a certain range, such as the age of 0-130 years, height 0 to 3 meters;

If we can specify the range of variables in the program, then we can quickly check out the data is not legal, and can make the program in the correct operation of saving a lot of unnecessary space;

1. Definition of a sub-boundary type: type

Child interface Type identifier = Lower bound. (Constant a).  Constant b); Upper and lower bounds must be of the same type, and upper bound must be greater than the nether ordinal

Definition and application of sub-boundary types