Ada Programming/Keywords/or


Ada. Time-tested, safe and secure.
Ada. Time-tested, safe and secure.

Logical operator

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Boolean operator

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X : Boolean := A < 10 or A > 20;

Boolean shortcut operator

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In the below example the function G is only called when F(X) returns the value False.

if F(X) or else G(Y) then

    Walk_The_Dog;
 
end if;

This shortcut operator is sometimes used to speed up the evaluation of boolean expressions, but the Ada Style Guide recommends to compare the performance of both forms before switching one to the other. In general, it is good idea to use or else in sake of performance only when the second expression involves a function call.

The or else form is also used when the second expression is known to raise an exception unless the first expression is False.

Unlike C/C++, Ada short-cut operators are not the standard way to evaluate boolean expressions. This is because Ada is designed to do by default what is generally safer, but lets the programmer request a different behaviour.

Boolean operator on arrays

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The or 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 or Y;

Bitwise operator

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

Select statement

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alternative

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See Ada Programming/Tasking#Selective waiting.

delay

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See Ada Programming/Tasking#Timeout.

See also

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Wikibook

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Ada 95 Reference Manual

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Ada 2005 Reference Manual

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Ada Quality and Style Guide

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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