Ada Programming/Keywords/or

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Contents 1 Logical operator 1.1 Boolean operator 1.2 Boolean shortcut operator 1.3 Boolean operator on arrays 1.4 Bitwise operator 2 Select statement 2.1 alternative 2.2 delay 3 See also 3.1 Wikibook 3.2 Ada 95 Reference Manual 3.3 Ada 2005 Reference Manual 3.4 Ada Quality and Style Guide

[edit] Logical operator

[edit] Boolean operator

X : Boolean := A < 10 or A > 20;

[edit] Boolean shortcut operator

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.

[edit] Boolean operator on arrays

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

[edit] Bitwise operator

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

[edit] Select statement

[edit] alternative

See Ada Programming/Tasking#Selective_waiting.

[edit] delay

See Ada Programming/Tasking#Timeout.

[edit] See also

[edit] Wikibook

• Ada Programming
• Ada Programming/Keywords
• Ada Programming/Operators

[edit] Ada 95 Reference Manual

• 2.9 Reserved Words (Annotated)
• 4.4 Expressions (Annotated)
• 4.5.1 Logical Operators and Short-circuit Control Forms (Annotated)
• Annex P (informative) Syntax Summary (Annotated)

[edit] Ada 2005 Reference Manual

• 2.9 Reserved Words (Annotated)
• 4.4 Expressions (Annotated)
• 4.5.1 Logical Operators and Short-circuit Control Forms (Annotated)
• Annex P (informative) Syntax Summary (Annotated)

[edit] Ada Quality and Style Guide

• 3.1.3 Capitalization

• 5.5.5 Short Circuit Forms of the Logical Operators
• 10.5.2 Short-Circuit Operators
• 10.6.3 Bit Operations on Modular Types

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 subtype all others synchronized (Ada 2005) and for out array function overriding (Ada 2005) tagged (Ada 95) at task generic package terminate begin goto pragma then body private type if procedure case in protected (Ada 95) until (Ada 95) constant interface (Ada 2005) use is raise declare range when delay limited record while delta loop rem with digits renames do mod requeue (Ada 95) xor

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