error C2679: binary '=' : no operator found which takes a right-hand operand of type 'std::vector<_Ty> *' (or there is no acceptable conversion)

Question

I've got the following when building a graph.

#include <vector>
using namespace std;

template<class T>
class Node
{
private:
  T data;
  Node<T> *link;
  vector<T>  neighbors;
public:
  Node(){neighbors = new vector<T>();};
};

int main()
{
  Node<int> n;
  return 0;
}

... which returns the error C2679: binary '=': no operator found...

I'm using VS2010. What's wrong? Thanks!

Answer 1

The new operator returns a pointer type, but your member variable neighbors is not a pointer. So you're assigning a pointer (the result of new ) to a non-pointer type. Your neighbors variable needs to be a pointer: vector<T>* neighbors .

But I think you're probably misunderstanding the use of new here. You probably shouldn't even use a vector pointer at all. Just remove the line neighbors = new vector<T>() . The vector object will be automatically initialized and ready for use.

In C++, the new keyword allocates and initializes objects on the heap, which then must be freed later using delete . It's preferable to avoid the new keyword by simply initializing the object as an automatic variable, like:

vector<T> neighbors;

This way, you don't have to worry about memory management, and the vector object will automatically be destroyed when it goes out of scope.

Answer 2

vector<T>  neighbors;
neighbors = new vector<T>();

neighbours is not a pointer.

The whole point of using vectors is not managing the memory explicitly. In fact in your node constructor, neighbours is default-initialized, so just don't initialize. Your constructor may look like this:

Node(){}

So you can just omit it :)