c++11 - C++: What is best way to destruct this code? -


i want know proper way of destructing code i'm facing many random issues. however, piece of code working i'm calling ~cacheframe() first , assinging nullptr pagemap inside ~lrucache()

#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 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();         (auto it: pagemap) {             cout << "deleting " << it.first << " 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};     (auto it: array) {         cache.accesspage(it);     }     return 0; }

c++: best way destruct code?

you mean free resources.

in case of unordered_map

the way right not it. unordered_map automatically release resources when it's destroyed allocated automatically.

unless allocated values new, don't delete them.

in case of linked list

~cacheframe() {     node *temp = head->next, *temp2;      while(temp != null)     {         temp2 = temp;         temp = temp->next;         delete temp2;     } }

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