initialization of data types in a std vector

Question

OK I am currently building a matrix using the std vectors that is meant to have a cell or bacteries on them. Because of this I made a "dead" class to be mother of cell and bacteries. So in the matrix a case that does not have either of them would be dead.

But when I try to build the matrix, by somthing like: world[x][y] = new cell()/world[x][y] = new bacterie(); it will not compile.

so my question is, how can I initialize it?

this is my code, its on spanish sorry.

matrizB[fila-1][columna-1] =  new BacteriaM();

matrizB its a

vector<vector <dead>> matrizB(n); 

and BacteriaM is a class that inherits from dead; n is defined by the user. (sorry for bad grammar and programing, i'm new to programing)

Answer 1

In order to use polymorphism, your matrix element must be a pointer .

vector<vector <dead*>> matrizB(n);

You will have to be careful to manage the memory of the elements. It might be worth looking at smart pointers ( std::shared_ptr or std::unique_ptr -- whichever is more correct).

Hope this helps.

Answer 2

The main issue that you are having is the new operator. I am assuming you are not accustomed to C++ when it comes to creating objects. The new operator for C++ does not simply create an object, but a pointer to an object. So, you can go matrix[x][y] = cell() or change to a vector< vector < dead* > > and follow what @Duthomhas says with selecting smart pointers. That way you can better manage memory especially when you are dealing with a vector of vectors.

Note: Watch out for cell() constructors! C++ will get confused and think you are declaring a function...