Sakura hat recht.
Und für die MultiSelect Variante:
Delphi-Quellcode:
procedure TForm1.FormCreate(Sender: TObject);
begin
for i := 0 to ListBox1.Items.Count - 1 do begin
if ListBox1.Selected[i] then begin
IdIcmpClient1.Host := ListBox1.Items.Strings[i];
IdIcmpClient1.Ping(IntToStr(timeout));
end;
end;
end;