Question

我想知道破解此代码的正确方法，因为我面临许多随机问题。但是，这条代码正在工作，因为我首先调用~CacheFrame()而不是nullptr pageMap ~LruCache()内#include <iostream> #include <unordered_map> #include <list> using namespace std; struct Node { int pageNumber; Node *next; Node *prev; Node(int pageNumber, Node *prev, Node *next) { this->pageNumber = pageNumber; this->next = next; this->prev = prev; } }; class CacheFrame { const size_t maxSize; int size; Node *head, *tail; public: CacheFrame(int maxSize) : maxSize(maxSize) { size = 0; head = tail = nullptr; } ~CacheFrame() { cout << "CacheFrame Destructor called" << endl; tail = nullptr; while (head) { Node *temp = head->next; head->next = nullptr; head->prev = nullptr; delete head; head = temp; } } void MovePageToFront(Node* page) { if (page == nullptr || page == head) { return; } if (page == tail) {// point tail to second last element tail = tail->prev; tail->next = nullptr; } page->prev->next = page->next; if (page->next) page->next->prev = page->prev; page->next = head; head->prev = page; head = page; } Node* InsertPage(int pageNumber) { Node *page = new Node(pageNumber, nullptr, nullptr); if (!head) { head = tail = page; size = 1; return head; } if (size < maxSize) { size++; } else { Node *temp = tail; tail = tail->prev; tail->next = nullptr; delete temp; } page->next = head; head->prev = page; head = page; return page; } size_t getCurrentSize() { return size; } size_t getMaxSize() { return maxSize; } int getLastPageNumber() { return tail->pageNumber; } void printFrame() { Node *start = head; cout << "Frame" << endl; while (start) { cout << "-----" << endl; cout << "| " << start->pageNumber << " |" << endl; start = start->next; } cout << "-----"<< endl; } }; class LruCache { const size_t size; CacheFrame frame; unordered_map<int, Node*> pageMap; public: LruCache(int size): size(size), frame(CacheFrame(size)) {} ~LruCache() { cout << "LruCache Destructor called" << endl; frame.~CacheFrame(); for (auto it: pageMap) { cout << "Deleting " << it.first << " from map" << endl; it.second = nullptr; pageMap.erase(it.first); // if (it.second) { // it.second->next = nullptr; // it.second->prev = nullptr; // delete it.second; // } } } void accessPage(int pageNumber) { cout << "Access Page : " << pageNumber << endl; if (pageMap.find(pageNumber) != pageMap.end()) {// page hit cout << "Page Hit" << endl; frame.MovePageToFront(pageMap[pageNumber]); } else {//page miss cout << "Page Miss" << endl; if (frame.getMaxSize() == frame.getCurrentSize()) { pageMap.erase(frame.getLastPageNumber()); } pageMap[pageNumber] = frame.InsertPage(pageNumber); } frame.printFrame(); } }; int main() { LruCache cache = LruCache(3); int array[] = {4,2,1,1,4,3,7,8,3}; for (auto it: array) { cache.accessPage(it); } return 0; }

print("Leaving definition : " + func._name_)

Answer 1

C ++：什么是破坏此代码的最佳方法？

你的意思是释放资源。

如果是unordered_map

正确行事的方法不是这样做。 unordered_map会在资源被自动分配时自动释放资源。

除非您使用new分配值，否则不会delete。

如果是linked list

~CacheFrame()
{
    Node *temp = head->next, *temp2;

    while(temp != NULL)
    {
        temp2 = temp;
        temp = temp->next;
        delete temp2;
    }
}

C ++：什么是破坏此代码的最佳方法？

1 个答案: