Manipulation

┌─────┬─────┬─────┬─────┬─────┬─────┐
| 92  | 97  | 98  | 99  | 98  | 94  |
└─────┴─────┴─────┴─────┴─────┴─────┘
   0     1     2     3     4     5

std::array<int, 6> marks = {92, 97, 98, 99, 98, 94};
// Print first element
std::cout << marks[0];
// Change 2th element to 99
marks[1] = 99;
// Take input from the user
std::cin >> marks[2];