c++ 程序在检查 p!=NULL 条件后结束（p 是一个指针）

Question

该程序以没有错误消息结束，它发生在 while(p!=NULL) 行之后，我使用了一些控制台消息来确定它在那里停止工作。

void refreshOnDataEntry(set<string> s, Node **front, Node **rear, set<set<string>> &currentSolution, set<string> &kSetUnion)
{
    set<string> currentShare;
    set<string>::iterator it;
    Node *p = *front;
    Node *data = new Node;
    data->S = s;
    data->unique = s;
    cout << "I'm about to die" << endl;
    while (p!=NULL)
    {
        currentShare = setIntersection(p->unique, data->unique);
        p->unique.erase(currentShare.begin(), currentShare.end());
        p->shared.insert(currentShare.begin(), currentShare.end());
        data->shared.insert(currentShare.begin(), currentShare.end());
        p = p->next;
    }
    currentShare = setIntersection(p->unique, data->unique);
    for (it = currentShare.begin(); it != currentShare.end(); ++it)
    {
        p->unique.erase(*it);
        p->shared.insert(*it);
        data->shared.insert(*it);
    }

    currentSolution.insert(s);
    kSetUnion.insert(data->S.begin(), data->S.end());

    if (*rear != NULL)
        (*rear)->next = data;
    else
        *front = data;
    *rear = data;
}

这个函数是从这个其他函数调用的

set<set<string>> maxSMod(set<set<string>> &F, set<string> U, int k)

重要环节：

    Node *front = NULL, *rear = NULL, *p;
    set<set<string>>::iterator it = F.begin();
    set<string> kSetsUnion;
    set<set<string>> currentSolution;
    for (i = 0; i < k; i++)
    {
        solution.insert(*it);
        refreshOnDataEntry(*it, &front, &rear, currentSolution, kSetsUnion);
        ++it;
    }