Pointer used in linked list operations

For example, when inserting an ordered linked list, we usually use two pointers to traverse the list, and then determine whether to insert the list at the first position; this special case does not need to be considered after pointer is used.
Code:

#include <stdio.h>#include <stdlib.h>struct node{    int data;    struct node *next;} *head;//sorted link-listvoid insert(struct node *new_node){    struct node *cur = head, *pre = NULL;    while(cur != NULL && cur->data < new_node->data){        pre = cur;        cur = cur->next;    }       new_node->next = cur;    if(pre == NULL)        head = new_node;    else        pre->next = new_node;}//use pointer to pointer can make things easiervoid insert2(struct node *new_node){    struct node **linkp = &head;    while(*linkp !=NULL && (*linkp)->data < new_node->data){        linkp = &(*linkp)->next;    }    new_node->next = *linkp;    *linkp = new_node;}void show(){    struct node *p = head;    while(p){        printf("%d , ", p->data);        p = p->next;    }}int main(){    int i;    struct node ns[] = {        {80, NULL},        {8, NULL},        {1, NULL},        {10, NULL},    };    for(i = 0; i < 4; i++){        insert2(&ns[i]);    }    show();    return 0;}

Next, let's look at this idea in hlist.