Ada Programming/Keywords/and

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Ada. Time-tested, safe and secure.

Logical operator


Boolean operator

X : Boolean := A > 10 and A < 20;

Boolean shortcut operator


Shortcut operators are used to make the evaluation of parts of boolean expressions conditional: and then, or else. This should never be done to speed up the evaluation (with modern optimizing compilers, it will possibly not have that effect). The correct use is to prevent the evaluation of expressions known to raise an exception.

if Dog /= null and then G (Dog) then
   Walk (Dog);
end if;

In the example above, G (Dog) is only called when the pointer Dog is not null, i.e. it actually points to something.

Actually and then and or else are not operators in the sense of the reference manual, they are called 'Short-circuit Control Forms'. The difference is that (true) operators can be redefined (i.e. overloaded), whereas these cannot. They are however defined for any boolean type.

Since Ada allows parallel evaluation of the arguments for an expression, shortcut operators are not the standard way of evaluating boolean expressions. In any case where the final result of the evaluation is guaranteed to be the same, the compiler is allowed to use a shortcut evaluation.

Boolean operator on arrays


The and operator is applied to each pair of boolean elements from the left and right arrays. The result has the same bounds as the left operand.

type Day_Of_Month is range 1 .. 31;            
type Month_Array is array (Day_Of_Month) of Boolean;

X : Month_Array := Function_1;
Y : Month_Array := Function_2;
Z : Month_Array := X and Y;

Bitwise operator


The operator and could be used with modular types to perform bitwise operations.

Adding interfaces to tagged types


This language feature is only available from Ada 2005 on.

type Programmer is new Person 
                   and Printable
     Skilled_In : Language_List;
   end record;

See also




Ada 95 Reference Manual


Ada 2005 Reference Manual


Ada Quality and Style Guide


Ada Keywords
abort else new return
abs elsif not reverse
abstract (Ada 95) end null
accept entry select
access exception of separate
aliased (Ada 95) exit or some (Ada 2012)
all others subtype
and for out synchronized (Ada 2005)
array function overriding (Ada 2005)
at tagged (Ada 95)
generic package task
begin goto parallel (Ada 2022) terminate
body pragma then
if private type
case in procedure
constant interface (Ada 2005) protected (Ada 95) until (Ada 95)
is use
declare raise
delay limited range when
delta loop record while
digits rem with
do mod renames
requeue (Ada 95) xor

Ada Operators
and and then > + abs &
or or else >= - mod
xor = < * rem in
not /= <= ** / not in