Object-oriented Software in Ada 95

56 Ada introduction: Part 2
Height_Metres is of subtype Metres, a range check is performed on the assigned value. No conversion is
required when Height_Metres is output as its type Metres is a subtype of Float.
An example of a user's interaction with the program is shown below:
Enter person's height in Inches 73.0
Height in Metres is 1.85
4.18 Relational operators
The logical comparison operators are:
= equal
/= not equal
< less than
> greater than
= greater than or equal
The relational operators are used to establish the truth of a relationship between two values. The result is of type
Boolean. For example:
with Ada.Text_Io, Ada.Integer_Text_Io;
use Ada.Text_Io, Ada.Integer_Text_Io;
procedure Main is
Temperature : Integer; --Temperature in Centigrade
Hot : Boolean; --Is it hot
begin
Get( Temperature );
if Temperature > 24 then
Put("It's warm"); New_Line;
end if;
Hot := Temperature > 30;
if Hot then
Put("It's hot"); New_Line;
end if;
end Main;
4.18.1 Boolean operators
Boolean values may be combined with the following operators:
and logical and Note: Both LHS and RHS evaluated
or logical or Note: Both LHS and RHS evaluated
and then logical and Note: RHS only evaluated if LHS TRUE
or else logical or Note: RHS only evaluated if LHS FALSE
xor
Exclusive or,
True xor False => True False xor True => True
True xor True => False False xor False => False
© M A Smith - May not be reproduced without permission