Returning two strings in C++ - c++

Question

I am solving exercises for a C++ exam I have soon. Consider the following exercise:
A travel agency uses lists to manage its trips. For each trip the agency registers its point of departure, point of arrival, distance and time/duration
1) Define the necessary structures to represent a list of trips
2) Write a function that, given integer i returns the point of departure and point of arrival of the trip in position i
Defining the structure is easy:
struct list{
char departure[100];
char arrival[100];
double distance;
double time;
list* next = NULL;
};
My problem is the function. The actual work, to find the ith trip is easy. But how can I return the two char arrays/strings departure and arrival? If this were a question in my exam, I would have solved it like this:
typedef list* list_ptr;
list_ptr get_trip(list_ptr head, const int i){
if(i<0 || head==NULL){
return NULL;
}
for(int k = 0; k<i;k++){
head = head->next;
if(head==NULL){
return NULL;
}
}
return head;
}
I am returning a pointer to the list element. One then has to print departure and arrival. I could easily return just the departure or just the arrival by using a function with return type char*. How can I properly return 2 strings?
I know that there is ways doing this using std::tuple, but I cannot use this as we haven't had it in the lecture(we only had the really basic stuff, up to classes).
Am I right that returning both strings is not possible without using additional libraries?
Cheers

Answer 1

OK, to start with, your list type has some problems. Don't use char[] in C++ unless you really, really have to (note: if you think you have to, you're probably wrong). C++ provides a standard library that is wonderous in its applications (well, compared to C), and you should use it. In particular, I'm talking about std::string. You're probably OK using double for distance and duration, although a lack of units means that you're going to have a bad time.
Let's try this:
struct Trip {
std::string departure;
std::string arrival;
double distance_km;
double duration_hours;
};
Now you can either use std::vector, std::list, std::slist, or roll your own list. Let's assume the last.
class TripList {
public:
TripList() = default;
// Linear in i.
Trip& operator[](std::size_t i);
const Trip& operator[](std::size_t i) const;
void append_trip(Trip trip);
void remove_trip(std::size_t i);
private:
struct Node {
Trip t;
std::unique_ptr<Node> next;
};
std::unique_ptr<Node> head;
Node* tail = nullptr; // for efficient appending
};
I'll leave implementation of this to you. Note that list and trip are separate concepts, so we're writing separate types to handle them.
Now you can write a simple function:
std::pair<string, string> GetDepartureAndArrival(const TripList& list, std::size_t index) {
const auto& trip = list[index];
return {trip.departure, trip.arrival};
}