| Description |
The While keyword starts a control loop that is executed as long as the Expression is satisfied (returns True).
The loop is not executed at all if the expression is false at the start.
You need Begin or End markers if multiple statements are required in the loop.
It is used when it is important that the statements are at only executed when necessary.
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| Related commands |
| Begin |
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Keyword that starts a statement block |
| Boolean |
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Allows just True and False values |
| Do |
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Defines the start of some controlled action |
| End |
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Keyword that terminates statement blocks |
| For |
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Starts a loop that executes a finite number of times |
| Repeat |
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Repeat statements until a ternmination condition is met |
| Until |
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Ends a Repeat control loop |
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| Example code : Display integer squares until we reach 100 |
// 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
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
num, sqrNum : Integer;
begin
num := 1;
sqrNum := num * num;
// Display squares of integers until we reach 100 in value
While sqrNum <= 100 do
begin
// Show the square of num
ShowMessage(IntToStr(num)+' squared = '+IntToStr(sqrNum));
// Increment the number
Inc(num);
// Square the number
sqrNum := num * num;
end;
end;
end.
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| Hide full unit code |
1 squared = 1
2 squared = 4
3 squared = 9
4 squared = 16
5 squared = 25
6 squared = 36
7 squared = 49
8 squared = 64
9 squared = 81
10 squared = 100
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