while and repeat in Delphi

One three-minute kiln countdown written twice, once in each loop form.

program WhileRepeat;
uses SysUtils;
var
  Minutes: Integer;
begin
  // while tests first, so a start of zero runs the body zero times.
  Minutes := 3;
  while Minutes > 0 do
  begin
    WriteLn(Format('kiln timer at %d', [Minutes]));
    Dec(Minutes);
  end;
  // repeat tests last, so the body always runs at least once.
  Minutes := 3;
  repeat
    WriteLn(Format('glaze timer at %d', [Minutes]));
    Dec(Minutes);
  until Minutes = 0;
  WriteLn('both timers reached zero');
end.

How it works

1. while Minutes > 0 do tests first, so a start of zero would print nothing at all.
2. repeat tests last at until Minutes = 0;, so its body always runs at least once.
3. Both bodies call Dec(Minutes) so the counter actually reaches the exit condition.

Keywords and builtins used here

• Dec
• Format
• Integer
• WriteLn
• begin
• do
• end
• program
• repeat
• until
• uses
• var
• while

The run, in numbers

Lines

20

Characters to type

444

Tokens

81

Three-star pace

80 tpm

At the three-star pace of 80 tokens a minute, this run takes about 61 seconds.

Type this snippet

Step 3 of 3 in Control flow, step 9 of 27 in Language basics.

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