View Compilation Error

0_0_38111843_22730.cpp: In function 'int main()':
0_0_38111843_22730.cpp:16:35: error: 'memset' was not declared in this scope
   memset(attend, 0, sizeof(attend));
                                   ^
0_0_38111843_22730.cpp:17:24: error: 'scanf_s' was not declared in this scope
   scanf_s("%d", &person);
                        ^