C++ MovieList array and pointer - c++

Question

I'm still a bit stuck on another part on my assignment.
Here is what the prompt is asking:
Now you can modify the LoadMovies function to create a MovieList
object and add each of the Movie objects to it. The function
LoadMovies should return a pointer to the MovieList object. That means
you need to create the MovieList object dynamically and on the heap.
Change the main function and store the returned MovieList pointer in a
variable. To test if everything works as expected, you can use the
PrintAll function of the MovieList object.
Here is my code so far:
class MovieList {
public:
Movie* movies;
int last_movie_index;
int movies_size;
int movie_count = 0;
MovieList(int size) {
movies_size = size;
movies = new Movie[movies_size];
last_movie_index = -1;
}
~MovieList() {
delete [] movies;
}
int Length() {
return movie_count;
}
bool IsFull() {
return movie_count == movies_size;
}
void Add(Movie const& m)
{
if (IsFull())
{
cout << "Cannot add movie, list is full" << endl;
return;
}
++last_movie_index;
movies[last_movie_index] = m;
}
void PrintAll() {
for (int i = 0; i < movie_count; i++) {
movies[last_movie_index].PrintMovie();
}
}
};
void ReadMovieFile(vector<string> &movies);
void LoadMovies();
enum MovieSortOrder
{
BY_YEAR = 0,
BY_NAME = 1,
BY_VOTES = 2
};
int main()
{
LoadMovies();
// TODO:
// You need to implement the Movie and MovieList classes and
// the methods below so that the program will produce
// the output described in the assignment.
//
// Once you have implemented everything, you should be able
// to simply uncomment the code below and run the program.
MovieList *movies = LoadMovies();
// // test methods for the Movie and MovieList classes
//PrintAllMoviesMadeInYear(movies, 1984);
//PrintAllMoviesWithStartLetter(movies, 'B');
//PrintAllTopNMovies(movies, 5);
//delete movies;
return 0;
}
void LoadMovies()
{
vector<string> movies;
ReadMovieFile(movies);
string name;
int year;
double rating;
int votes;
for (int i = 0; i < movies.size(); i++)
{
istringstream input_string(movies[i]);
getline(input_string, name, '\t');
input_string >> year >> rating >> votes;
Movie movie (name, year, votes, rating);
movie.PrintMovie();
}
}
Now where I'm stuck at is where the professor asks me to modify the LoadMovies in the prompt and turn it into a pointer. I'm drawing blanks. Also for some reason if I try to compile it says:
C:\Users\Andy\Documents\C++ Homework\MovieStatisticsProgram\MovieStatsProgram.cpp:163: error: void value not ignored as it ought to be
MovieList *movies = LoadMovies();
^

Answer 1

The order of your constructor is wrong
MovieList(int size) {
movies = new int[movies_size]; // movies_size hasn't been initialized yet!
movies_size = size;
last_movie_index = -1;
}
It should be
MovieList(int size)
: movies_size{size}, movies{new int[size]}, last_movie_index{0}
{}
Though as #ScottMcP-MVP noted your array should be
Movie* movie;
So your constuctor would be
MovieList(int size)
: movies_size{size}, movies{new Movie[size]}, last_movie_index{0}
{}
Some advice for getting started on the remaining functions
Length function will return how many are current used from last_movie_index.
IsFull will check if last_movie_index == movies_size - 1
Add will need to use last_movie_index to figure out what element in your array to store the movie.
PrintAll will have to iterate from [0] to [movie_count] and print out each element.
Your Add function would look something like
void MovieList::Add(Movie const& m)
{
if (IsFull())
{
std::cout << "Cannot add movie, list is full" << std::endl;
return;
}
movies[last_movie_index] = m; // assigns a copy to your array
++last_movie_index; // Increment the movie index
}