CODEWITHSUNDEEP
c++vectormultiple-inheritancederived-class
Rob Simpson
Rob Simpson

Reputation: 45

Vector of pointers to base class within a derived class

I'm writing an application where I will have several derived classes accessed through pointers to a base class. I wish for one of these derived classes to contain a vector of pointers it's neighbors (also of the base class type) in the application, like so: 

    #include <vector>

    class BaseClass
    {
    public:
        BaseClass() { }
        virtual ~BaseClass() { }
    };

    class DerivedClass : virtual public BaseClass
    {
    public:
        DerivedClass() : BaseClass() { }
        ~DerivedClass() { }
    private:
        vector<BaseClass*> Neighbors;
    };

However, get the following compiler error:

example.cpp:16: error: ISO C++ forbids declaration of ‘vector’ with no type
example.cpp:16: error: expected ‘;’ before ‘<’ token

Is this even possible? If it is possible please someone point out my mistake! The compiler should know what type a BaseClass is as it has just been declared, in fact declaring a member of type BaseClass Foo; works, so I don't understand why the vector cannot recognise BaseClass*.

Cheers!

Upvotes: 3

Views: 669

Answers (2)

Scottymac
Scottymac

Reputation: 476

Intended to be a comment on Answer #1: You should avoid "using ..." declarations in header files. Keep them inside implementation files (.cpp). Google's Style Guideline provides some additional information that the original poster and answer-er may find helpful: http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Namespaces. I don't endorse the google styles as a whole.

Upvotes: 1

Qaz
Qaz

Reputation: 61970

You didn't put either using namespace std;, using std::vector, or std::vector<...>...

#include <vector>
using std::vector; //choice 1
using namespace std; //choice 2 

class BaseClass
{
public:
    BaseClass() { }
    virtual ~BaseClass() { }
};

class DerivedClass : virtual public BaseClass
{
public:
    DerivedClass() : BaseClass() { }
    ~DerivedClass() { }
private:
    std::vector<BaseClass*> Neighbors; //choice 3
};

Upvotes: 5

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