Mega Code Archive
Dec - decrement an ordinal variable system unit
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1 procedure Dec ( var Variable : Ordinal variable ) ;
2 procedure Dec ( var Variable : Ordinal variable; Count : Integer ) ;
Description
The Dec procedure decrements the ordinal Variable parameter passed to it.
You can decrement :
Characters
Non-floating number types
Enumeration types
Pointers
The decrement is by the base size of the unit. For example, decrementing a Pointer will be by 4 bytes if the pointer points to Words.
Version 1 of Inc decrements by 1 unit.
Version 2 of Inc decrements by Count units.
Notes
Dec is equivalent in performance to simple subtraction, or the Pred procedure.
Count can be negative.
Related commands
Inc Increment an ordinal variable
Pred Decrement an ordinal variable
Sqr Gives the square of a number
Sqrt Gives the square root of a number
Succ Increment an ordinal variable
Succ Increment an ordinal variable
Sum Return the sum of an array of floating point values
Example code : Decrementing characters, numbers and enumerations
type
TSuit = (Hearts, Clubs, Diamonds, Spades);
var
Character : char;
Number : Integer;
Card : TSuit;
begin
// We can decrement characters
Character := 'B';
ShowMessage('Character : '+Character);
Dec(Character);
ShowMessage('Character-1 : '+Character);
// We can decrement numbers
Number := 23;
ShowMessage('Number : '+IntToStr(Number));
Dec(Number, 5);
ShowMessage('Number-5 : '+IntToStr(Number));
// We can decrement enumerations
Card := Clubs;
ShowMessage('Card starts at Clubs');
Dec(Card);
if Card = Hearts then ShowMessage('Card is now Hearts');
if Card = Clubs then ShowMessage('Card is now Clubs');
if Card = Diamonds then ShowMessage('Card is now Diamonds');
if Card = Spades then ShowMessage('Card is now Spades');
end;
Show full unit code
Character : B
Character-1 : A
Number : 23
Number-5 : 18
Card starts at Clubs
Card is now Hearts
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