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Description
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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
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Begin
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Keyword that starts a statement block
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Boolean
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Allows just True and
False values
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Do
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Defines the start of some controlled action
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End
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Keyword that terminates statement blocks
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For
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Starts a loop that executes a finite number
of times
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Repeat
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Repeat statements until a ternmination
condition is met
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Until
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Ends a Repeat control loop
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Example code : Display
integer squares until we reach 100
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// 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
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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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