| Description |
The Boolean type provides an enumeration of the logical True and False values.
Unlike other languages, it is not a number - it will only allow these values. This makes the code much more reliable.
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| Notes |
Using calculations to test for true or false is a C like practice, but is supported in Delphi. Use the following to hold such a logical number:
ByteBool
WordBool
LongBool
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| Related commands |
| And |
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Boolean and or bitwise and of two arguments |
| If |
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Starts a conditional expression to determine what to do next |
| Not |
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Boolean Not or bitwise not of one arguments |
| Or |
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Boolean or or bitwise or of two arguments |
| Xor |
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Boolean Xor or bitwise Xor of two arguments |
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| Example code : Boolean assignments and tests |
// 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
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
same : Boolean;
small, large, i : Integer;
begin
small := 23;
large := 455555;
// Test directly to see if these numbers are the same size
if small = large
then ShowMessage('small = large')
else ShowMessage('small <> large');
// Use a Boolean to hold and test this outcome
same := (small = large);
if same
then ShowMessage('small = large')
else ShowMessage('small <> large');
// Assign a direct logical value to this Boolean
same := True;
if same
then ShowMessage('same is True')
else ShowMessage('same is False');
end;
end.
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| Hide full unit code |
small <> large
small <> large
same is True
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