[C++]Alocarea dinamica a memoriei interne

#include <iostream>

using namespace std;

struct nod {
    long info;
    nod *urm;
};
nod *u, *q, *p, *prim;

void creare() {
    p = new nod;
    prim = p;
    cout<<"Dati informatia nodului: ";
    cin>>p->info;
    p->urm = NULL;
    while(p->info != 0) {
        u = new nod;
        cout<<"Dati informatia: ";
        cin>>u->info;
        p->urm = u;
        p = u;
    }
        p->urm = NULL;
}

void afis_sd() {
    p = prim;
    while(p->urm != NULL) {
        cout<<p->info<<" ";
        p = p->urm;
    }
}

void sterge(){
    long int nr;
    cout<<"Dati nodul de sters: ";
    cin>>nr;
    p = prim;
    if(p->info == nr) {
        q = p;
        p = p->urm;
        prim = p;
        delete(q);
    }
    else {
        p = prim;
        while(nr != p->urm->info) {
            p = p-> urm;
        }
        q = p->urm;
        p->urm = q->urm;
        delete(q);
    }
}
void inserare() {
    long int nr;
    q = new nod;
    p = prim;
    cout<<"Dati informatia nodului de inserat: ";
    cin>>q->info;
    cout<<"Dati informatia nodului dupa care se face inserarea: ";
    cin>>nr;
    while(p->info != nr) {
        p = p->urm;
    }
    q->urm = p->urm;
    p->urm = q;
}
int main() {
    creare();
    afis_sd();
    cout<<'\n';
    inserare();
    afis_sd();
    cout<<'\n';
    sterge();
    afis_sd();
    return 0;
}