{"id":9338,"date":"2022-09-18T11:33:39","date_gmt":"2022-09-18T06:03:39","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-pointers-class-c\/"},"modified":"2022-09-18T11:33:39","modified_gmt":"2022-09-18T06:03:39","slug":"solved-pointers-class-c","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-pointers-class-c\/","title":{"rendered":"[Solved] Pointers\/Class C++"},"content":{"rendered":"

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You need a doubly-linked list. This list uses a node class, in this case you can call it train<\/code>. Each node has a name<\/code>, as well as next<\/code> and previous<\/code> node. The list class will store the nodes.<\/p>\n

The example below is a simple version where all the members are public<\/code>. You can improve it by declaring next<\/code>, prev<\/code>, head<\/code>, tail<\/code> as private<\/code>, then provide public<\/code> methods to access them.<\/p>\n

The list should also cleanup after itself. In add<\/code> method there is a call to train *node = new train(s)<\/code>. This memory should be freed in destructor using delete<\/code>. You have to walk the list and delete the memory for each node.<\/p>\n

See also these references:
https:\/\/en.wikipedia.org\/wiki\/Doubly_linked_list<\/a>
http:\/\/www.dailyfreecode.com\/Code\/double-linked-list-cpp-3422.aspx<\/a><\/p>\n

class train\n{\npublic:\n    string name;\n    train *next, *prev;\n    train(const string &s) {name = s; next = prev = nullptr;}\n};\n\nclass linked_list\n{\npublic:\n    train *head, *tail;\n    linked_list() { head = tail = nullptr;  }\n    linked_list() { \/*add cleanup routine*\/ }\n    train* add(const string &s)\n    {\n        train *node = new train(s);\n        if(!head) {\n            head = tail = node;\n        }\n        else {\n            node->prev = tail;\n            tail->next = node;\n            tail = node;\n        }\n        return node;\n    }\n};\n\nint main()\n{\n    linked_list list;\n    train *walk, *node = nullptr;\n    string name;\n    while(true) {\n        char choice=\"a\";\n        if(node) {\n            cout << \"(A)dd, (L)ist, (N)ext, (P)revious, (Q)uit ?\\n\";\n            cin >> choice;\n            choice = tolower(choice);\n        }\n\n        switch(choice) {\n        case 'a': \n            cout << \"enter name:\\n\";\n            cin >> name;\n            node = list.add(name);\n            break;\n        case 'l': \n            cout << \"list:\\n\";\n            walk = list.head;\n            while(walk) {\n                cout << walk->name << \"\\n\";\n                walk = walk->next;\n            }\n            break;\n        case 'n':\n            if(node->next) {\n                node = node->next;\n                cout << \"next: \" << node->name << \"\\n\";\n            }\n            break;\n        case 'p':\n            if(node->prev) {\n                node = node->prev;\n                cout << \"previous: \" << node->name << \"\\n\";\n            }\n            break;\n        default: break;\n        }\n        if(choice == 'q')\n            break;\n    }\n    return 0;\n}\n<\/code><\/pre>\n<\/p><\/div>\n
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solved Pointers\/Class C++ <\/p>\n","protected":false},"excerpt":{"rendered":"
[ad_1] You need a doubly-linked list. This list uses a node class, in this case you can call it train. Each node has a name, as well as next and previous node. The list class will store the nodes. The example below is a simple version where all the members are public. You can improve … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[324],"class_list":["post-9338","post","type-post","status-publish","format-standard","hentry","category-solved","tag-c"],"yoast_head":"\n[Solved] Pointers\/Class C++ - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-pointers-class-c\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Pointers\/Class C++ - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] You need a doubly-linked list. This list uses a node class, in this case you can call it train. 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