| Description |
The Double type is the general purpose floating point type in Delphi. It strikes the balance between capacity/precision versus storage/performance.
It supports approximately 15 digits of precision in a range from 2.23 x 10-308 to 1.79 x 10308.
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| Notes |
The Single type is smaller and faster, but with reduced capacity and precision.
The Extended type has the highest capacity and precision, but biggest storage and worst performance.
A Double set to its highest value is treated as Infinity.
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| Related commands |
| Currency |
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A floating point type with 4 decimals used for financial values |
| Extended |
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The floating point type with the highest capacity and precision |
| Single |
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The smallest capacity and precision floating point type |
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| Example code : Showing the precision and capacity of Double values |
// 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
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
account1, account2, account3, account4 : Double;
begin
account1 := 0.1234567890123456789; // 20 decimal places
account2 := 1.234567890123456789E308; // Highest exponent value
account3 := account1 + account2;
account4 := 9.9E308; // Treated as infinite
ShowMessage('Account1 = '+FloatToStr(account1));
ShowMessage('Account2 = '+FloatToStr(account2));
ShowMessage('Account3 = '+FloatToStr(account3));
ShowMessage('Account4 = '+FloatToStr(account4));
end;
end.
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| Hide full unit code |
Account1 = 0.123456789012346
Account2 = 1.23456789012346E308
Account3 = 1.23456789012346E308
Account4 = INF
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