function FieldCount(dbf :integer): integer;

FieldCount returns a number of fields in a dbf file.
Be careful. The first field has a number 0 and the last field has a number FieldCount-1.

var
  dbf :integer;
begin
  dbf := OpenBase( 'filename.dbf' );
  if dbf <> 0 then
  begin
    showmessage( FieldCount(dbf) );
    CloseBase(dbf);
  end;
end.