char *_getcwd(char *buffer, int maxlen); //ANSI版本 wchar_t *_wgetcwd(wchar_t *buffer, int maxlen ); //Unicode版本 参数说明 buffer: Storage location for the path. maxlen:Maximum length of the path in characters: char for _getcwd and wchar_t for _wgetcwd.Returns a pointer to buffer.A NULL return value indicates an error, and errno is set either to ENOMEM,
indicating that there is insufficient memory to allocate maxlen bytes
(when a NULL argument is given as buffer), or to ERANGE, indicating that the path is longer than maxlen characters.
If maxlen is less than or equal to zero, this function invokes an invalid parameter handler, as described in Parameter Validation.