HELP OR Revised: Fran Evelyn Jul 1985
Updated: Adrian Howard Mar 1992
The infix operator -or- is used to form a "disjunction" of two
expressions. For example:
list = [] or hd(list) = "a"
The expression
<P> or <Q>
is the value of <P> unless <P> is -false-, when it is the value of <Q>.
In other words, unless both <P> and <Q> evaluate to -false-, the
expression is true (since POP-11 treats as -true- any value which is not
-false-).
Normally OR will be used with *BOOLEAN expressions, when it can be
treated as a logical OR operation.
There is also a bitwise logical 'or' operator (||) on integers treated
as sequences of "bits", see REF *NUMBERS/Bitwise details.
Also see:
HELP *AND --- Forming conjunctions in POP-11
HELP *BOOLEAN --- Boolean expressions and values
HELP *CONDITIONALS --- Summary of POP-11 conditional statements
REF *RECORDS/Booleans --- Full information on "booleans"
--- C.all/help/or
--- Copyright University of Sussex 1992. All rights reserved. ----------