打印值的输出不一致 在这个程序中，我克隆了C++中的一个图。 这是我的程序，接下来是问题和问题区域 #include <vector> #include <unordered_map> #include <queue> #include <iostream> using namespace std; #define neighbours neighbors // Definition for a Node. class Node { public: int val; vector<Node*> neighbors; Node() { val = 0; neighbors = vector<Node*>(); } Node(int _val) { val = _val; neighbors = vector<Node*>(); } Node(int _val, vector<Node*> _neighbors) { val = _val; neighbors = _neighbors; } }; #define neighbours neighbors class Solution { public: Node* cloneGraph(Node* node) { // BFS queue <Node*> q; // add starting vec q.push(node); Node *curr; int value; vector <int> visited; unordered_map <int, Node*> umap; while(!q.empty()) { curr = q.front(); q.pop(); visited.push_back(curr->val); //cout << curr->val << "-"; // create new node Node *newNode = new Node(curr->val); // add new node val and addr to umap umap[value] = newNode; // clone neighbour list vector <Node*> nlist; //vector <Node*> list = curr->neighbours; // make copy of given list for(Node* node: curr->neighbours) { value = node->val; //cout << value << " "; // search in map first, if exists take addr else make and insert into // list if(umap.find(value) == umap.end()) { umap[value] = new Node(value); } nlist.push_back(umap[value]); if(find(visited.begin(), visited.end(), value) == visited.end()) { q.push(node); } } cout << endl; newNode->neighbours = nlist; // copy nlist to nodes list part } // starting of new node = umap[1]; return umap[1]; } }; int main() { Node ob1; Node ob2; ob1.val = 1; ob2.val = 2; vector <Node*> nlist; nlist.push_back(&ob1); ob2.neighbours = nlist; nlist.pop_back(); nlist.push_back(&ob2); ob1.neighbours = nlist; Solution obj; Node *sv = obj.cloneGraph(&ob1); cout << sv->val << "-"; for(Node *node : sv->neighbours) { cout << node->val << endl; } cout << &ob1 << " " << sv << endl; }

当我保持原样时，输出是

1-0x7ffee561e4e0 0x7fb1ba402840

---

我还试着注释掉

cout
umap[value]=newNode通过访问未初始化的变量
值
显示未定义的行为

实际上，
value
包含一些恰好位于堆栈上的垃圾。对程序中看似不相关的部分所做的更改会影响堆栈的内容，从而影响
value
的初始值，并最终影响上述未定义行为的显示方式

1-0x7ffee561e4e0 0x7fb1ba402840

1-