Question

我有这两个类，我希望边缘节点成为图形的朋友，但我不知道如何声明它

图表的实现基于邻接列表，我使用unique_ptr进行自动删除。

#ifndef GRAPH_HPP
#define GRAPH_HPP

#include <memory>
using std::unique_ptr;

template<typename Type>
class edgenode {
    friend class graph<Type>; //here
public:
    edgenode(Type w, int adj);
    ~edgenode() {};
private:
    Type                            mWeight;
    int                             mAdj;
    unique_ptr<edgenode<Type>>      mNext;
};

template<typename Type>
edgenode<Type>::edgenode(Type w, int adj)
    :mWeight(Type), mAdj(adj) {
    mNext = nullptr;
}

///-------------------------------------------------///

template<typename Type>
class graph {
public:
    graph(int maxvertices = 1000, bool directed = false);
    ~graph();
private:
    unique_ptr<edgenode<Type>>* mEdges;
    int*                        mDegree;
    int                         mNoOfNodes;
    int                         mNoOfVertices;
    int                         mSize;
    bool                        m_bDirected;
};

template<typename Type>
graph<Type>::graph(int maxvertices = 1000, bool directed = false)
    : mSize(maxvertices),
    m_bDirected(directed),
    mNoOfNodes(0),
    mNoOfVertices(0)
{
    mDegree = new int[mSize];
    mEdges = new unique_ptr<edgenode<Type>>[mSize];


    for (int i = 0; i < mSize; ++i) {
        mDegree[i] = 0;
        mEdges[i] = nullptr;
    }
}

template<typename Type>
graph<Type>::~graph() {
    delete[] mEdges;
    delete[] mDegree;
}
#endif

Answer 1

转发声明类模板，如下所示：

override bindIXtextBuilderParticipant() {
    MyBuilderParticipant
}

Answer 2

在edgenode声明之前添加template class graph<class T>;，它被称为前向声明：

#include <memory>
using std::unique_ptr;

template class graph<class T>; // this

template<typename Type>
class edgenode {
    friend class graph<Type>; //here
public:
    ...

如何在定义之前将类朋友声明为另一个

2 个答案: