Question

我在以下代码中从此行获得断言失败“list iterator not dereferencable”：

iter2 = iter-＆gt; vertex_list.erase（iter2）;

我不确定为什么会这样，我确保列表不是空的。完整代码如下：

void Map_Quad_List::Vertex_List_Duplicate_Removal() {
    for (std::list<Map_Polygon>::iterator iter = map_polygon_list.begin(); iter != map_polygon_list.end(); iter++) { //iterate through polygons
        std::vector<XMFLOAT3> position_list; //list of vertices already tried
            for (std::list<Vertex>::iterator iter2 = iter->vertex_list.begin(); iter2 != iter->vertex_list.end(); iter2++ ) {//iterate through vertices
                bool dup = false;
                for (std::vector<XMFLOAT3>::iterator pos_list_iter = position_list.begin(); pos_list_iter != position_list.end(); pos_list_iter++) { //check vertex against position_list
                    if ((!position_list.empty()) && (XMFLOAT3_Comparison(*pos_list_iter, iter2->position))) { //if vertex already exists in position_list
                        iter2 = iter->vertex_list.erase(iter2); //remove vertex from polygon's vertex_list
                        dup = true;
                    }
                }
                if (dup == false) //if there is not a duplicate in position_list, add it to position_list
                position_list.push_back(iter2->position);
            }

    }
}

map_polygon_list是类类型Map_Polygon

的std ::列表

Map_Polygon类有一个类型为Vertex的std :: list

Vertex是一个由XMFLOAT3（位置）和XMFLOAT4（颜色）组成的类，此函数仅处理位置（XMFLOAT3）

XMFLOAT3_Comparison是一个比较两个XMFLOAT3的函数，如果它们是相同的则返回true

Answer 1

看起来iter2可能会转到最内部for循环中的iter->vertex_list.end()，这会导致此断言，因为指向的项为null。

断言失败，列出迭代器而不是dereferencable

1 个答案: