Simple Struct definition in C for Red Black Tree - c

Question

I don't use the C language since years and now I need it again.
I'm trying to build a Red-Black Tree but I'm stuck at the beginning because I'm missing something about "structs".
Take a look to my "structs" declarations please, they are easy.
This is a header file included in Red_black_tree.c
#define BLACK 0 //defalut color
#define RED 1 //
struct Node { //create a black node by default, to have a red one look at "create_red_node"
struct Node *left = NULL;
struct Node *right= NULL;
int key = 0;
int value = 0;
char color = BLACK;
};
struct Root_t {
struct Node* Root;
};
struct Node* create_node () {
struct Node* black = (Node*) malloc (sizeof(Node));
return black;
}
struct Node* create_red_node () {
struct Node* red = create_node ();
red->color=RED;
return red;
}
Root_t* create_tree () {
struct Root_t* fake=(Root_t*) malloc (sizeof(Root_t));
struct fake->Root->left=create_red_node ();
struct fake->Root->right=create_red_node ();
return fake;
}
I compiled with "gcc Red_black_tree.c -o RBTree".
GCC says something like : "expected ';' at end of declaration list" 7 times, or "must use 'struct' tag to refer to type... ", "expected identifier...".
What do you think, is it good to create RBTree?

Answer 1

In C, you can not assign while you define the members of a struct
Instead of
struct T {
int a = 1;
int b = 2;
};
you need something like
struct T {
int a;
int b;
};
...
struct T t = {.a = 1, .b = 2};
In addition, all your members are set to 0 (NULL is an alias of (void *)0), when you want to allocate memory and initialize all to zero at the same time you can use calloc
struct Node* black = calloc(1, sizeof(*black)); // Dont cast malloc and friends
And here:
struct fake->Root->left=create_red_node();
, you don't want the struct keyword, instead:
fake->Root->left=create_red_node();
Another suggestion: do not hardcode the data of the red-black-tree in the structure, (int key, value;) even if it works you end up with a non reusable container, instead, use a generic pointer to void (void *data;) and a callback to your comparison functions in the implementation.
struct Node *insert(struct Node *root, int (*comparer)(const void *, const void *)) ...