Moodle Linked Lists Exercises

#include <stdio.h>

typedef struct _nodes{
    int num;
    struct _nodes *link;
} nodes;

void printList(nodes *f){
    if (f==NULL)
        return;
    printf("%i ", f->num);
    printList(f->link);
}

int nodesNumber(nodes *f){
    int count=0;
    while (f!=NULL){
        count++;
        f=f->link;
    }
    return count;
}

nodes *first;

void addFront(int x){
    nodes *p=(nodes*)malloc(sizeof(nodes));
    p->num=x;
    p->link=first;
    first=p;
}

void addAt(int index, int x){
    nodes *p=first;
    int i;
    for (i=0; i<index-1; i++)
        p=p->link;
    nodes *ip=(nodes*)malloc(sizeof(nodes));
    ip->num=x;
    ip->link=p->link;
    p->link=ip;
}

void reverse(nodes *f, nodes *prev){
    if (f->link==NULL){
        first=f;
        f->link=prev;
        return;
    }
    reverse(f->link, f);
    f->link->link=f;
    f->link=prev;
}

int main(void) {
    first=(nodes*)malloc(sizeof(nodes));
    first->num=1;
    first->link=(nodes*)malloc(sizeof(nodes));
    first->link->num=5;
    first->link->link=(nodes*)malloc(sizeof(nodes));
    first->link->link->num=19;
    first->link->link->link=(nodes*)malloc(sizeof(nodes));
    first->link->link->link->num=32;
    first->link->link->link->link=(nodes*)malloc(sizeof(nodes));
    first->link->link->link->link->num=2;
    first->link->link->link->link->link=(nodes*)malloc(sizeof(nodes));
    first->link->link->link->link->link->num=4;
    first->link->link->link->link->link->link=NULL;
    printf("Initial list:\n");
    printList(first);
    printf("\nNumber of nodes: %i\n", nodesNumber(first));
    printf("\nInserting 8 at the beginning:\n");
    addFront(8);
    printList(first);
    printf("\nNumber of nodes: %i\n", nodesNumber(first));
    printf("\nInserting 7 at position 3:\n");
    addAt(3, 7);
    printList(first);
    printf("\nNumber of nodes: %i\n", nodesNumber(first));
    printf("\nReverse:\n");
    reverse(first, NULL);
    printList(first);
    printf("\nNumber of nodes: %i\n", nodesNumber(first));
    return 0;
}