尝试创建指向对象内部先前对象的指针

Question

I'm attempting to create a vector of pointers to Nodes, where each node stores a pointer to the previous Node in the list.

I made a small test program to see if I could access a variable gscore in the previous object to the one I call.

#include <iostream>
#include <vector>

using namespace std;

struct Node
{
    Node(int gscore1)
    {
        gscore = gscore1;
    }

    Node *previous;
    int gscore;
};

int main()
{
    std::vector<Node*> nodeVec;

    Node *tempnode;
    tempnode = new Node(10);
    Node *tempnode2;
    tempnode = new Node(11);

    nodeVec.push_back(tempnode);
    nodeVec.push_back(tempnode2);

    nodeVec[1]->previous = tempnode;

    cout << nodeVec[1]->previous->gscore << endl;

    return 0;
}

However this results in a crash. What is the correct way to do this?

Answer 1

You never initialize tempnode2. You initialize tempnode twice.

int main()
{
    std::vector<Node*> nodeVec;

    Node *tempnode;
    tempnode = new Node(10);
    Node *tempnode2;
    tempnode2 = new Node(11); // <<---- HERE

    nodeVec.push_back(tempnode);
    nodeVec.push_back(tempnode2);

    nodeVec[1]->previous = tempnode;

    cout << nodeVec[1]->previous->gscore << endl;

    return 0;
}

Answer 2

Looks like a typing error. The third line in main() should be tempnode2 not tempnode.