creare afisare inserare stergere liste duble

#include <iostream>
#include  <fstream>

using namespace std;

ifstream f("date.in");

struct nod
{
    int info;
    nod *dr,*st;
};

nod *prim,*ultim;

void creare()
{
    nod *nou;
    int x;
    while (f>>x)
        if (prim==NULL)
        {
            prim=new nod;
            prim->info=x;
            prim->st=NULL;
            ultim=prim;
        }
        else
        {
            nou=new nod;
            nou->info=x;
            ultim->dr=nou;
            nou->st=ultim;
            ultim=nou;
        }
        ultim->dr=NULL;
}

void parcurge()
{
    nod *p=prim;
    while(p)
    {
        cout<<p->info<<" ";
        p=p->dr;
    }
}

void inserare()
{
    nod *p=prim,*nou;

    while (p->dr)
    {
        if (p->info%2==0)
        {
          nou=new nod;
          nou->info=60;
          nou->dr=p->dr;
          nou->st=p;
          p->dr->st=nou;
          p->dr=nou;
          p=p->dr;
        }
        p=p->dr;
    }
}

void sterge()
{
    nod *p=prim,*q,*r;
    while (p->dr)
    {
        if (p->dr->info==2)
        {
            q=p->dr;
            r=q->dr;
            p->dr=r;
            r->st=p;
            delete q;
        }
        p=p->dr;
    }
}

int main()
{
    creare();
    sterge();
    parcurge();
    return 0;
}