C - linked list removing values on insertion - c

Question

I'm trying to create a method that lets me insert a new node in my liked list at a chosen index,
it is currently working as intended when inserting into index 0 or 1 but when I try to insert into any index >= 2 the first value in the list is being lost. any ideas why?
example main:
#include <stdio.h>
#include <stdlib.h>
#include "list.h"
int main( void ) {
List list = new_list();
add(list, "Three");
add(list, "Two");
add(list, "Zero");
print_list(list);
printf("Inserting at 1 \n");
insert_at(list, 1, "one")
print_list(list);
printf("Inserting at 2 \n");
insert_at(list, 2, "inserted")
print_list(list);
header file:
typedef struct Node{
char *value;
struct Node *next;
}Node;
typedef Node** List;
List new_list();
Node *new_node(char *value);
void add(List list,char *value);
int is_empty(List list);
void print_list(const List list);
int insert_at(List list,int index,char *value);
method file:
#include <stdlib.h>
#include <stdio.h>
#include "list.h"
#include <string.h>
List new_list(){
List list = malloc(sizeof(List));
*list = NULL;
return list;
}
Node *new_node(char *value){
Node *node = malloc(sizeof(Node));
node->value = value;
node->next = NULL;
return node;
}
void add(List list,char *value){
if (*list == NULL){
*list = new_node(value);
}else {
Node *node = new_node(value);
node->next = *list;
*list = node;
}
}
int is_empty(List list){
if (*list == NULL){
return 1;
} return 0;
}
void print_list(const List list){
printf("[");
Node *curr = *list;
if (curr == NULL){
printf("]\n");
return;
}
while (curr->next != NULL){
printf("\"%s\", ", curr->value );
curr = curr->next;
}
printf("\"%s\"", curr->value );
printf("]\n");
}
int insert_at(List list,int index,char *value){
if ((index > 0 && is_empty(list) == 1) || index < 0){
return 0;
}
int i= 0;
if (index == 0){
add(list, value);
return 1;
}
while((*list) != NULL){
//advancing loop
i++;
//checking if wanted index = lists index
if (i == index){
//creating new node
Node *node = new_node(value);
//updating next values;
node->next = (*list)->next;
(*list)->next = node;
return 1;
}
(*list) =(*list)->next;
}
return 0;
}
example output:
["Zero", "Two", "Three"]
Inserting at 1
["Zero", "One", "Two", "Three"]
Inserting at 2
["One", "INSERTED", "Two", "Three"]

Answer 1

In this while loop
while((*list) != NULL){
//advancing loop
i++;
//checking if wanted index = lists index
if (i == index){
//creating new node
Node *node = new_node(value);
//updating next values;
node->next = (*list)->next;
(*list)->next = node;
return 1;
}
(*list) =(*list)->next;
}
the statement
(*list) =(*list)->next;
overwrites the pointer to the head node that results at least in numerous memory leaks.
And the second function parameter should have an unsigned integer type as for example size_t.
Also the function new_list should look at least like
List new_list(){
List list = malloc(sizeof( *list ));
*list = NULL;
return list;
}
In general it is a bad approach with using such a typedef
typedef Node** List;
It only confuses readers of the code.