std::vector iterator incompatibles

I have an error (vector iterator incompatibles) during execution in my C++ program that I do not understand. [ (Windows / Visual C++ 2008 Express) ]

Here is a simplified version of my problem :

#include <vector>

class A
{
    int mySuperInt;
public:
    A(int val) : mySuperInt(val) {}
};
class B
{
    std::vector<A*> myAs;
    public:
        B() 
        {
            myAs.push_back(new A(1));
        };
        const std::vector<A*> getA() const {return myAs;}
};

int开发者_运维百科 main()
{
    std::vector<B>* myBs = new std::vector<B>;

    myBs->push_back(B());

    std::vector<B>::const_iterator it_B = myBs->begin();
    for ( ; it_B != myBs->end(); ++it_B)
    {
        std::vector<A*>::const_iterator it_A = it_B->getA().begin();
        for ( ; it_A != it_B->getA().end(); ++it_A) // <-- Error during execution: vector iterator incompatibles
        {
            // Do stuff
            // ...
        }
    }
}

Did I missed something ?

Thanks in advance for your answers.

Your getA() function returns a vector by value. You're initializing your loop iterator to the beginning of that vector, but since the returned vector is temporary, it is destroyed at the end of that line.

// at the end of this line the vector returned by getA is gone, so it_A is invalid.
std::vector<A*>::const_iterator it_A = it_B->getA().begin();

Therefore the iterator is no longer valid. You should instead return a reference to the vector like this (note the &):

const std::vector<A*> & getA() const {return myAs;}

You realize that B::getAs() returns a copy of its myAs. So the vector that it_A ranges over is a different copy than the one whose getA().end() it keeps being compared to... I.e. the for loop never stops. (Even worse, it_A ranges over a vector<> that is a temporary, so it's destroyed and all kinds of random crap could be written over that storage while you're pretending to iterate through it.)

Thanks for the complete and simple repro. The problem here is that you're using iterators from 2 different vectors, this is a runtime debug check.

You probably didn't intend to do this, but it is a result of the return type of getA.

You're returning a copy of the vector and your probably meant to return a reference to the vector, like this:

const std::vector<A*>& getA() const {return myAs;}