// main.cpp

#include <iostream>
#include "SomeObject.h"

using namespace std;

int main()
{

    SomeObject someObj;

    vector<int> & vec = someObj.getSomeVectorReference();

    cout << vec.size() << endl;
    return 0;
}

// SomeObj.cpp

#include "SomeObject.h"

using namespace std;

SomeObject::SomeObject()
{
    //ctor
}

SomeObject::~SomeObject()
{
    //dtor
}

vector<int> & SomeObject::getSomeVectorReference()
{
    vector<int> returnVec;

    for (int i = 0; i < 10; i++)
        returnVec.push_back(i);

    return returnVec;
}

// SomeObj.h

#ifndef SOMEOBJECT_H
#define SOMEOBJECT_H

#include <vector>

class SomeObject
{
    public:
        SomeObject();
        virtual ~SomeObject();

        std::vector<int> & getSomeVectorReference();

    protected:

    private:
};

#endif // SOMEOBJECT_H