| Description |
The PDateTime type is a pointer to a TDateTime value.
Pointer arithmetic, such as Inc, Dec can be used on it, for example to navigate a block of TDateTime values, as in the example.
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| Related commands |
| Dec |
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Decrement an ordinal variable |
| Inc |
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Increment an ordinal variable |
| TDateTime |
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Data type holding a date and time value |
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| Example code : Store 3 TDateTime values in memory and navigate through them |
// Full Unit code.
// -----------------------------------------------------------
// You must store this code in a unit called Unit1 with a form
// called Form1 that has an OnCreate event called FormCreate.
unit Unit1;
interface
uses
// The System unit does not need to be defined
DateUtils, SysUtils,
Forms, Dialogs;
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm} // Include form definitions
procedure TForm1.FormCreate(Sender: TObject);
var
dateTimePtr : PDateTime;
a : TDateTime;
begin
// Allocate storage for three date time variables
GetMem(dateTimePtr, 3 * SizeOf(Extended));
// Fill out these date time variables
dateTimePtr^ := Yesterday;
Inc(dateTimePtr);
dateTimePtr^ := Date;
Inc(dateTimePtr);
dateTimePtr^ := Tomorrow;
// Now display these values
Dec(dateTimePtr, 2);
ShowMessage('Yesterday = '+DateToStr(dateTimePtr^));
Inc(dateTimePtr);
ShowMessage('Today = '+DateToStr(dateTimePtr^));
Inc(dateTimePtr);
ShowMessage('Tomorrow = '+DateToStr(dateTimePtr^));
end;
end.
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| Hide full unit code |
Typical program output:
Yesterday = 10/04/2003
Today = 11/04/2003
Tomorrow = 12/04/2003
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