Generate random number of queues

Just out of curiosity, how does someone create a random number of queues?

I have a constructor like so from my current project:

public:

Passenger<NODETYPE> *super_express;
Passenger<NODETYPE> *express_line1;
Passenger<NODETYPE> *express_line2;
Passenger<NODETYPE> *regular_line;

Checkout_Simulation() : super_express("Super Express Counter 01"),
                            express_line1("Express Line Counter 01"),
                            express_line2("Express Line Counter 02"),
                            regular_line("Regular Line Counter 01"),
                            clock_time(0), finish_time(0) {}

How do you use a random generated number to create a random number of the regular_line queues? In other words, the random generator comes out as 5 which will make 5 regular_lines?

This is where they are run:

template <typename NODETYPE>
void Checkout_Simulation<NODETYPE> :: run_sim() {

    for(clock_time = 0; clock_time <total_time; clock_time++){
            item_obj.item_purchase(number);

    if (number < 15) {
      super_express.check_new_arrival(clock_time, display_all);
    // number = the value
      super_express.number = number;
    }
    else if (number >15 && number <=20){

      express_line1.check_new_arrival(clock_time, display_all);
      express_line2.check_new_arrival(clock_time, display_all);
    }
    else {
      regular_line.check_new_arrival(clock_time, display_all);
    }



    if (clock_time >= finish_time){
            start_checkout();
      }

    }//end for loop
}