freepascal.compiler/docs/refex/ex69.pp

Program Example69;

{ Program to demonstrate the Swap function. }
Var W : Word;
    L : Longint;
    
begin
  W:=$1234;
  W:=Swap(W);
  if W<>$3412 then 
    writeln ('Error when swapping word !');
  L:=$12345678;
  L:=Swap(L);
  if L<>$56781234 then 
    writeln ('Error when swapping Longint !');
end.