CODEWITHSUNDEEP
c++linked-list
Stefan
Stefan

Reputation: 113

Pointer error in Linked list?

I want to create a linked list with integeres and between each two nodes I want to create another node that is the average between the one before and the one after.

In my add function I don't understand why my p pointer is at the last element in the linked list and not at the first. (this is why I think it crashes).

Thank you.

#include<iostream>
using namespace std;

struct Nod{
    int info;
    Nod* urm;
};

void create(const int &a, Nod *&p, Nod *&u)
{
    if (p == NULL)
    {
        p = new Nod;
        p->info = a;
        u = p;
    }
    else
    {
        Nod *q;
        q = new Nod;
        q->info = a;
        u->urm = q;
        u = q;
    }
    u->urm = NULL;
}

void print(Nod *p)
{
    while (p->urm)
    {
        cout << p->info<<" -> ";
        p = p->urm;
    }
    cout << p->info;
}

void add(Nod *p)
{
    while (p)
    {
        Nod *q;
        q = new Nod;
        q->info = (p->info + p->urm->info) / 2;
        q->urm = p->urm;
        p->urm = q;
        p = p->urm->urm;
    }
}

int main()
{
    Nod *p, *u;
    p = u = NULL;

    char *numar;
    numar = new char[100];
    cout << "Enter a number: "; cin >> numar;
    for (int i = 0; (unsigned)i <= strlen(numar) - 1; i++)
        create(numar[i] - '0', p, u);
    add(p);
    print(p);

    system("Pause");
    return 0;
}

Upvotes: 0

Views: 85

Answers (1)

Pranit Kothari
Pranit Kothari

Reputation: 9841

You need to add,

if(p->urm!=0)// this line
        q->info = (p->info + p->urm->info) / 2;

Because p->urm could be NULL.

I tried in Visual Studio after adding suggested line, and it is working fine. Though I do not understand what will you get by adding two addresses.

Upvotes: 1

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