Name
Pred Function
Syntax
function Pred(const Value): Ordinal type
;
Description
The Pred
function returns the predecessor of an
ordinal value, usually an enumerated value. That is, it returns the
enumerated value whose ordinal value is one less than
Value
. Pred
is not a real
function.
Tips and Tricks
Dec
,Pred
, and subtraction by one have similar performance, so choose the one that you find most clear and easy to read.Calling
Pred(Low(
SomeType
))
raises runtime error 4 (ERangeError
). Without overflow checking, though,Pred
returns a value with the desired ordinal value, even though that value is not valid for the type.
Example
type TDay =
(Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday);
var
Day: TDay;
begin
...
Day := Pred(Day);
...
See Also
Dec Procedure, High Function, Inc Procedure, Low Function, Succ Function, $OverflowChecks Compiler Directive, $Q Compiler Directive |
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