D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(223): error:  #20: identifier "size_t" is undefined
      size_t mbsnrtowcs(wchar_t * __restrict /*dst*/,
D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(225): error:  #20: identifier "size_t" is undefined
                        size_t /*nmb*/,
D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(226): error:  #20: identifier "size_t" is undefined
                        size_t /*len*/, mbstate_t * __restrict /*ps*/) __attribute__((__nonnull__(2)));
D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(227): error:  #20: identifier "size_t" is undefined
      size_t wcsnrtombs(char * __restrict /*dst*/,
D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(229): error:  #20: identifier "size_t" is undefined
                        size_t /*nwc*/,
D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(230): error:  #20: identifier "size_t" is undefined
                        size_t /*len*/, mbstate_t * __restrict /*ps*/) __attribute__((__nonnull__(2)));
D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(257): error:  #20: identifier "size_t" is undefined
                       const wchar_t * __restrict /*s2*/, size_t /*n*/) __attribute__((__nonnull__(1,2)));
D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(259): error:  #20: identifier "size_t" is undefined
                       const wchar_t * __restrict /*s2*/, size_t /*n*/) __attribute__((__nonnull__(1,2)));
D:SoftwareKeil_v5ARMARMCCBin..includewchar.h(261): error:  #20: identifier "size_t" is undefined
                        const wchar_t * __restrict /*s2*/, size_t /*n*/) __attribute__((__nonnull__(1,2)));
..HARDWAREw25qxx.c: 0 warnings, 30 errors
"..OBJdemo.axf" - 270 Error(s), 0 Warning(s).

加错头文件引起的血案！！！！