c++ - 间歇性 “Vector iterator not dereferencable”

我有以下代码，但是在运行它时，我间歇性地收到“调试断言失败”错误，其原因是“ vector 迭代器不可取消”。

我要对该程序进行的操作是创建一堆2D形状(正方形和圆形)，然后将它们一个接一个地移动，检查碰撞的过程。当两个形状发生碰撞时，我希望将它们删除，直到(最多)剩下一个形状。大约每3次尝试中就有1次导致成功的结果，程序会发现四个碰撞，然后停止。其他时候，它将发现1-3次碰撞，然后出错。

我还应该提到我对C++比较陌生(是的，这是一个类(class)作业)，因此，如果我的代码中还有其他菜鸟错误，请指出这些错误!

我自己的移动和碰撞方法看起来不错，因此这里未包括它们。

Square * s1 = new Square(seedCoord(limit), seedCoord(limit), 2.0);
... //There is 9 new shapes created here (squares and circles)

std::vector<Shape*> shape;
shape.push_back(s1);
... //All 9 shapes added to the vector

int m = shape.size();
bool collision = false;

while(m>1) //Keep running until only one shape hasn't collided
{
    for (auto i=shape.begin(); i!=(shape.end());) //Perform move on each shape in sequence
    {
        collision = false; //Set collision boolean to false

        (*i)->move(seedCoord(0.5), direction[(rand() % 4)], limit); //Perform move on shape

        for (auto j=shape.begin(); j!=(shape.end()-1);) //Check for collision with each shape in sequence
        {
            if((*i) != (*j)) //Ignore self when checking for collision
            {
                if((*i)->collide(*j)) //Check for collision
                {
                    std::cout << "Collision between " << (*i) << " and " << (*j) << "\n";
                    m=m-2; //Lower shapes count by two (ie remove two collided shapes)
                    delete *i; //Delete pointer to initial shape
                    i = shape.erase(i); //Erase shape object
                    delete *j; //Delete pointer to collided shape
                    j = shape.erase(j); //Erase shape object
                    collision = true; //Set collision boolean to true
                    break; //Break out of internal for-loop (shape has been deleted so no more checks are necessary)
                }
                else
                {
                    j++; //If no collision, move onto next shape
                }
            }
            else
            {
                j++; //If i=j, move onto next shape
            }
        }
        if(!collision) //If no collision with any shape, move onto next shape
        {
            i++; //If no collision with any shape, move onto next shape
        }
        else
        {
            break; //If collision has occurred, break out of external for-loop (shape has been deleted so no more checks are necessary)
        }
    }
}

最佳答案

引用cpprefernce on erase:



我的猜测是，当您第二次调用erase(j)时，就会发生问题，j是一个迭代器，它引用i和shape.end()之间的位置并被无效。