Question

我的程序有问题。我在C ++中创建了一个Graph类，现在我想在拓扑上对它进行排序。问题是，我的拓扑排序接受任何DirectedGraph，但是当我想给它一个孩子（例如AdjacencyListDirectedUnweightedGraph）时，它拒绝转换。这是我的.hpps：

TopoSort.hpp：

#ifndef TOPOSORT_HPP
#define TOPOSORT_HPP

#include "../Graph.hpp"
#include "../DirectedGraph/AdjListUWDG.hpp"
#include "../DirectedGraph/DirectedGraph.hpp"
#include "../UnDirectedGraph/AdjListWUDG.hpp"

class TopoSort
{
protected:
    std::vector<int> _sortedList;
    std::vector<int> _KahnTopNodes;
public:
    TopoSort();
    ~TopoSort();
    void KahnSort(DirectedGraph &list);
    void KahnSortTopNodes(DirectedGraph &list);
};

#endif

DirectedGraph.hpp

#ifndef DIRECTEDGRAPH_HPP
#define DIRECTEDGRAPH_HPP

#include <iostream>
#include <string>
#include <vector>
#include "../Graph.hpp"

class DirectedGraph
: public Graph
{
protected:
    std::vector<int> _inDegree;
    std::vector<int> _outDegree;
public:
    DirectedGraph(){};
    virtual ~DirectedGraph(){};
    int     inDegree(int a){return (_inDegree[a]);}
    int     outDegree(int a){return (_outDegree[a]);}
    bool    rangeCheck(int a, int b)
    {
        if (a >= _vertices || b >= _vertices || a == b)
        {
            std::cout << "The edge " << a << " - " << b << " is invalid." << std::endl;
            return (false);
        }
        return (true);

    }
};

#endif

AdjListDG.hpp

#ifndef ADJListDG_HPP
#define ADJListDG_HPP

#include <string>
#include <vector>
#include "DirectedGraph.hpp"

class AdjListDG
: public virtual DirectedGraph
{
protected:
    std::vector<std::vector<std::pair<int, int> > > _adjList;
public:
    virtual ~AdjListDG();
    bool    existsEdge(Edge);
    bool    existsEdge(int, int);
    void    putEdge(Edge);
    void    removeEdge(Edge);
    int     adjacentVertices(int);
    bool    areAdjacent(int, int);
};

#endif

AdjListUWDG.hpp

#ifndef AdjListUWDG_HPP
#define AdjListUWDG_HPP

#include <string>
#include <vector>
#include "AdjListDG.hpp"

class AdjListUWDG
: public virtual AdjListDG
{
public:
    AdjListUWDG(std::string);
    virtual ~AdjListUWDG();
};

#endif

而且，我的主要。

#include <iostream>
#include <string>
#include <fstream>
#include "UnDirectedGraph/AdjListWUDG.hpp"
#include "UnDirectedGraph/AdjListUWUDG.hpp"
#include "UnDirectedGraph/AdjMatWUDG.hpp"
#include "UnDirectedGraph/AdjMatUWUDG.hpp"
#include "Assgn3/TopoSort.hpp"


int main(int argc, char** argv)
{
    if (argc != 2)
    {
        std::cout << "Usage : ./graph FILENAME" << std::endl;
        return(0);
    }

    std::string filename = argv[1];
    AdjListWUDG gr(filename);
    TopoSort tsort;
    std::ofstream fichier("results.txt", std::ios::out | std::ios::trunc);
    if(fichier)
    {
        if (gr.existsEdge(1, 2))
            fichier << "1 - 2 exist" << std::endl;
        fichier << "numedge == " << gr.numEdges() << std::endl;
        fichier << "adjver 1 == " << gr.adjacentVertices(1) << std::endl;
        fichier << "adj 1 2 == " << gr.areAdjacent(1,2) << std::endl;
        fichier << "adj 1 0 == " << gr.areAdjacent(1,0) << std::endl;
        fichier << "adj 0 2 == " << gr.areAdjacent(0,2) << std::endl;
    }    
    DirectedGraph * gr2 = &gr;
    tsort.KahnSort(*gr2);
}

就是这样！我很抱歉，如果它看起来很明显或什么的，我只是看不出有什么问题。还试过动态和静态演员，没有成功。提前谢谢！

编辑：

我是傻瓜。试图投射参考，而不是对象本身......

static_cast而不是static_cast

抱歉这个无用的帖子！

Answer 1

转换为引用而不是对象本身，这是愚蠢的，对不起！

C ++中的向上转换：无法将子类指针转换为父类指针

1 个答案: