Infinite loop

An infinite loop (also known as an endless loop or unproductive loop or a continuous loop) is a loop which never ends. Inside a loop, statements are repeated forever.

There are two implementations of an infinite loop:

while true do
begin
    // loop body repeated forever
end;

repeat
begin
    // loop body repeated forever
end
until false;

Break statement

“While true do” or “repeat until false” loops look infinite at first glance, but there is a way to escape the loop through the break statement.

var
  i:integer;
begin
  i := 0;
  while true do
    begin
      i := i + 1;
      if i = 100 then break;
    end;
end;

var
  i:integer;
begin
  i := 0;
  repeat
    i := i + 1;
    if i = 100 then break;
  until false;
end;

Optimization

If you really need an infinite loop, it is better to use repeat … until false;, since it shifts all instructions of the body “less” to the right (at least, if there is more than one statement in the loop).

See also

• true
• false
• repeat until
• while do
• break
• continue

From the Free Pascal wiki, page "Infinite loop", as it stood on 2023-01-04 after a change by Paskal, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's Licensing page. If you have concerns about this material, message the admin.