System.Dec
Delphi
procedure Dec(var X: Integer); overload;
procedure Dec(var X: Integer; N: Integer); overload;
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| procedure | public | System.pas | System | System |
Description
Decrements a variable by 1 or N.
In Delphi code, Dec subtracts one or N from a variable.
X is a variable of an ordinal type (including Int64), or a pointer type if the extended syntax is enabled.
N is an integer-type expression.
X decrements by 1, or by N if N is specified, for example:
On some platforms, Dec may generate optimized code, especially useful in tight loops.
If X is a pointer type, it decrements X by N times the size of the type pointed to. Thus, given:
type
PMyType = ^TMyType;
and
var
P: PMyType;
The statement Dec(P) decrements P by SizeOf(TMyType).
Warning: Do not use Dec on ordinal-type properties if the property uses a write procedure.