c - implementing a binary search tree - "incompatible types when returning type 'struct item_t *'..." -

i'm trying implement binary search tree holds inventory of ordered stock. stocked item attributes stored in nodes such:

typedef struct item item_t; struct item{     char name;     int price;     int quantity;     item_t *left;     item_t *right; }; 

the idea prompt user enter above attributes, , add entered item node. i've written far:

item_t *root = null; item_t *current_leaf = null;  void prompt_user(){     /*     in here contains code prompts user item attributes     , stores in variable called input     */     insert_node(input); }  void insert_node(char *input){     /*if tree doesnt have root...*/     if (root == null){          /*create one...*/         root = create_node(input);     }      else{         item_t *cursor = root;         item_t *prev = null;         int is_left = 0;         int comparison;          while(cursor != null){              /*comparison 1 key of input less key                of cursor, , 2 otherwise...*/             comparison = compare(input, cursor);             prev = cursor;              if(comparison == 1){                 is_left = 1;                 cursor = cursor->left;             }             else if (comparison == 2){                 is_left = 0;                 cursor = cursor->right;             }         }          if(is_left){             *prev->left = create_node(input);             current_leaf = prev->left;         }         else{             *prev->right = create_node(input);             current_leaf = prev->right;         }     } }  item_t create_node(char *input){      item_t *new_node = (item_t*)malloc(sizeof(item_t));      if (new_node == null){         printf("out of memory. shutting down.\n");         exit(exit_failure);     }      /*add data node...*/     update_item(input, new_node);      new_node->left = null;     new_node->right = null;      current_leaf = new_node;      return new_node; } 

i want root pointing first item ever entered, , current_leaf pointing last item processed. compare returns 1 if item being processed (input) less last processed item (current_leaf). update_item sets data new nodes (leaves).

the above isn't complete, it's i'm @ moment. i'm struggling work out how write add_node , how keep current_leaf updated correctly.

when try compile following errors:

$ gcc -ansi -pedantic -wall -o proj2.exe proj2.c  proj2.c: in function 'insert_node':  proj2.c:416:14: error: incompatible types when assigning type'structitem_t *' type 'item_t'          root = create_node(input);                ^  proj2.c: in function 'create_node':  proj2.c:470:5: error: incompatible types when returning type 'struct item_t *' 'item_t' expected       return new_node;       ^ 

item_t create_node(char *input) 

should be

item_t *create_node(char *input) 

what return structure should returning pointer of type struct item.