uses dos;
const
s:string='*.ab';
var
fr:SearchRec;
Attr:word;
f:file;
begin
 Attr:=AnyFile-Directory;
 FindFirst (s,Attr,fr);
 if DosError = 0 then
 begin
  repeat;
  assign (f,fr.Name);
  erase (f);
  FindNext (fr);
  until DosError <> 0;
 end;
end.