CODEWITHSUNDEEP
c++cstructlinked-listdoubly-linked-list
Gabe Clark
Gabe Clark

Reputation: 23

How might I be able to access a nested struct within a doubly linked list?

I am trying to use a doubly linked list with a header struct. I believe the header struct is simply supposed to hold a count of how many structs have been created in the list, and the first and last nodes. Now I see two problems. One is connecting the header struct to the subsequent structs and the second is accessing a nested struct that i have within my list nodes (sentry). If anyone could shed some light on what I might be doing wrong it would be greatly appreciated. Code is below. 

#include <iostream>
using namespace std;
typedef struct sentry sentry; 

struct stud{
    string name;
    char grade;
};

struct slist {
    int length;
    sentry *first;
    sentry *last;
};

struct sentry {
    slist *list;
    sentry *next;
    sentry *prev;
    stud *student;
};

int main(int argc, char** argv) {
    slist list;
    sentry *n;

    n = new sentry;

    // Full initialization of the header node.
    list.first = n;
    list.last = n;
    list.length = 0;

    n->prev = NULL;
    n->next = NULL;
    n->list = list->last;
    n->student->name = "test";
    n->student->grade = 'A';

    cout << n->student->name << '\n';
    cout << n->student->grade << '\n';

    return 0; 
}

Upvotes: 1

Views: 302

Answers (1)

Santiago Varela
Santiago Varela

Reputation: 2237

Why don't you modify your struct sentry to not include slist *list? Why is having a 2-way relationship between sentry and slist necessary? It makes it tedious to maintain, to read and update the values inside the list of the sentry. Nevermind, deallocating the memory on the heap to avoid memory leaks. Why not have slist (the header) only have information about the sentry. In this way you remove the complexity of a double binding between sentry and slist.

 struct sentry {
        sentry *next;
        sentry *prev;
        stud *student;
 };

Upvotes: 1

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