Which STL Container will be good to store millions of user define(class) data?

Question

Suppose we've millions of custom data that need to be stored and search later these which STL will be good? let's say

class A{ 
    public:
      int i;
      float f;
      string s;
};

We need to to store the objects of class A.

Answer 1

Which STL Container will be good to store millions of user define(class) data?

All of them, except for std::array .

and search later

Depends on the kind of searching. The associative containers have efficient lookup operations.