Method SetLength

include/rapidjson/document.h:1495–1495

        inline static bool Usable(SizeType len) { return            (MaxSize >= len); }
        inline void     SetLength(SizeType len) { str[LenPos] = (Ch)(MaxSize -  len); }
        inline SizeType GetLength() const       { return  (SizeType)(MaxSize -  str[LenPos]); }
    };  // at most as many bytes as "String" above => 12 bytes in 32-bit mode, 16 bytes in 64-bit mode