c - Creating a Node for Linked List/Self Referential Structures -

i'm trying create node create linked list, i'm getting error

"intellisense: value of type "void *" cannot assigned entity of type "c"" isn't value of c synonym b: null not void? therefore shouldn't initial node created null , manipulation of linked list occur?

i haven't continued insert function because creation of node not working

#include <stdio.h> #include <stdlib.h>  struct {     char data;     struct *nextptr; };  typedef struct b; typedef b *c;  void insert(c *sptr, char value); void print(c cptr); void menu(void);  int main (void) {     menu();     c startptr = null;     char c;     int x;     (x = 0; x <6; x++)     {         insert(&startptr, c);         print(startptr);     } }  void menu(void) {     puts("enter 1 add: \nenter 2 remove \nenter 3 quit"); }  void print (c cptr) {     puts("names in list");     printf("%c ->",cptr->data); }  void insert(c *sptr, char value) {     c nptr;     c pptr;     c cptr;     nptr = malloc( sizeof (b)); }