Name
Dec Procedure
Syntax
procedure Dec(var Variable); procedure Dec(var Variable; Count: Integer);
Description
The
Dec
procedure decrements a variable. You can
decrement any ordinal-type variable or pointer-type variable. You
cannot use Dec
to decrement a floating-point
variable.
Decrementing a pointer adjusts the pointer by the size of the base
type. For example, decrementing a pointer to
AnsiChar
decreases the pointer value by 1, and
decrementing a pointer to WideChar
decreases the
pointer value by 2.
The default is to decrement the variable by 1 unit, but you can
supply an integer to decrement by a different amount. When
decrementing a pointer, Count
is multiplied by the
size of the base type.
The Dec
procedure is built-in and is not a real
procedure.
Tips and Tricks
Count
can be negative, in which case the variable’s value increases.There is little performance difference between
Dec
,Pred
, or subtraction. That is, the following all result in similar object code:
Dec(X); X := Pred(X); X := X - 1; // if X is an integer or PChar type
You cannot use a property for the variable because a property value cannot be used as a
var
parameter. Use a simple assignment instead.
See Also
High Function, Inc Procedure, Low Function, Pred Function, Succ Function |
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