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.

 Related commands  Begin   Keyword that starts a statement block  Boolean   Allows just True and False values  Do   Defines the start of some controlled action  End   Keyword that terminates statement blocks  For   Starts a loop that executes a finite number of times  Repeat   Repeat statements until a ternmination condition is met  Until   Ends a Repeat control loop 

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Example code : Display integer squares until we reach 100  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;
 Show 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 

