[Mick]

function CountChars(Str:string; car:Char):integer;
var
 Ptr:PChar;
begin
  Result:= 0;
  Ptr:= PChar(Str);
  while Ptr^<>#0 do begin
    if Ptr^=car then Inc(Result);
    Inc(Ptr);
  end;
end;

Salud2 !!!