{文件名变小写}
function LowerCase(const S: string): string;
var
Ch: Char;
L: Integer;
Source, Dest: PChar;
begin
L := Length(S);
SetLength(Result, L);
Source := Pointer(S);
Dest := Pointer(Result);
while L <> 0 do
begin
Ch := Source^;
if (Ch >= 'A') and (Ch <= 'Z') then Inc(Ch, 32);
Dest^ := Ch;
Inc(Source);
Inc(Dest);
Dec(L);
end;
end;