c - Odd problem with pointer while implementing a linked list -

i'm trying implement linked list in c, , want store head node in separate struct. however, seems head node being reassigned somehow whenever add node.

#include <stdio.h> #include <stdlib.h>  struct bc_node {     struct bc_node *next;     void *data; }; struct bc_list {     struct bc_node *head;     struct bc_node *tail; };  void bc_list_push(struct bc_list *list, void *data) {     struct bc_node *node = calloc(1, sizeof(struct bc_node));      if (list->head != null)         printf("head: %d\n", *((int *) (list->head)->data));      node->next = null;     node->data = data;     if (list->head == null) {         printf("head null.\n");         list->head = node;     }     if (list->tail != null) {         (list->tail)->next = node;     }     list->tail = node;      printf("head: %d\n", *((int *) (list->head)->data)); }  int main(void) {     int i;     struct bc_list *list = calloc(1, sizeof(struct bc_list));      list->head = null;     list->tail = null;     (i = 0; < 3; i++)         bc_list_push(list, &i);     return 0; } 

the output:

head null. head: 0 head: 1 head: 1 head: 2 head: 2 

your data member pointer variable i in main, when print *data see value of counter during round of loop. nodes have same data value!