提示s[2],s[3]语法错误

因为这两个函数没有你写的那种用法

Delphi syntax:
function DateTimeToStr(DateTime: TDateTime): string; overload;
function DateTimeToStr(DateTime: TDateTime; const FormatSettings: TFormatSettings): string; overload;
C++ syntax:
extern PACKAGE AnsiString __fastcall DateTimeToStr(const System::TDateTime DateTime);
extern PACKAGE AnsiString __fastcall DateTimeToStr(const System::TDateTime DateTime, const TFormatSettings FormatSettings);
Description
The first form of DateTimeToStr is not thread-safe, because it uses localization information contained in global variables. The second form of DateTimeToStr, which is thread-safe, refers to localization information contained in the FormatSettings parameter. Before calling the thread-safe form of DateTimeToStr, you must populate FormatSettings with localization information. To populate FormatSettings with a set of default locale values, call GetLocaleFormatSettings.这个是Delphi自带的开发文档，我也没看见有这种用法的啊。
也就是说DateTimeToStr重载只有2种，一种是你的S[3]调用情况，对应的是function DateTimeToStr(DateTime: TDateTime): string; overload;
第二种情况，我自己也没有用过，但是根据开发文档显示TFormatSettings并不是string类型的。