Vector Iterators Incompatible

I have a class with a std::vector data member e.g.

class foo{
public:

const std::vector<int> getVec(){return myVec;} //other stuff omitted

private:
std::vector<int> myVec;

};

Now at some part of my main code I am trying to iterate through the vector like this:

std::vector<int>::const_iterator i = myFoo.getVec().begin();
while( i != myFoo.getVec().end())
{
   //do stuff
   ++i;
}

The moment I reach this loop, I get the aforementioned error.

The reason you are getting this, is that the iterators are from two (or more) different copies of myVec. You are returning a copy of the vector with each call to myFoo.getVec(). So the iterators are incompatible.

Some solutions:

Return a const reference to the std::vector<int> :

const std::vector<int> & getVec(){return myVec;} //other stuff omitted

Another solution, probably preferable would be to get a local copy of the vector and use this to get your iterators:

const std::vector<int> myCopy = myFoo.getVec();
std::vector<int>::const_iterator i = myCopy.begin();
while(i != myCopy.end())
{
  //do stuff
  ++i;
}

Also +1 for not using namespace std;

You are returning a copy of the vector. Because you are returning by value - your call to begin() and end() are for completely different vectors. You need to return a const & to it.

const std::vector<int> &getVec(){return myVec;}

I would do this slightly differently though. I'd make the class act a little like a standard container

class Data
{
   public:
      typedef std::vector<int>::const_iterator const_iterator;

      const_iterator begin() const { return myVec.begin(); }
      const_iterator end() const { return myVec.end(); }
};

Data::const_iterator i=myFoo.begin();

while(i != myFoo.end())
{
//
}