c - Red Black Tree - Initialization -

how can correctly initialize red black tree in c?

structure:

typedef struct node{     int key;     struct node *left;     struct node *right;     struct node *parent;      enum {red, black} color; }node;  typedef struct rbtree{     struct node *root;     struct node *nil; }rbtree; 

main function:

int main(){     rbtree *tree;     init_rbtree(&tree); } 

init function:

void init_rbtree(rbtree **t){     (*t)->root = null;      node *n = (node*)malloc(sizeof(node));     if(n != null){         n->color = black;         (*t)->nil = n;     } } 

the program crashes run code.

you need allocate memory *t before can use it.

void init_rbtree(rbtree **t) {     *t=malloc(sizeof(rbtree));      if (*t==null) {         //handle error     }       else {         (*t)->root = null;          node *n = malloc(sizeof(node));         if(n != null){             n->color = black;             (*t)->nil = n;         }     } }