Stack implementation using LinkList?

Question

What is Stack
A stack is a ADT which has LIFO i.e. last in first out behavior. Which means the element which is enetered at the later would be accessed at first. A Stack has two basic operations which are called push and pop which are used to store and retrieve data from the stack.

Required Functions
Though only push and pop are the necessary function but lets define the following function for the stack implementation in C using LinkList.

int stack_size()
struct node * create_node(int data)
void push(int data) 
void pop()
void traverse_stack()

Sample Code

struct node
{
    int data;
    struct node *next;
};

struct node *top;
int length= 0;

int stack_size()
{
    printf("\n No. of elements in stack : %d", length);
    return length;
}

struct node * create_node(int data)
{
    struct node *new;

    new = (struct node*)malloc(sizeof(struct node));
    new->next = null;
    new->data = data;

    length++;

    return new;
}

void push(int data)
{
    struct node *new;
    new = create_node(data);

    if (top == NULL)
    {
        top = new;
    }
    else
    {
        new->next = top;
        top = new;
    }
}

void pop()
{
    struct node *temp_top;

    temp_top = top;

    if (temp_top == NULL)
    {
        printf("\n Error : Trying to pop from empty stack");
        return;
    }
    else
        temp_top = temp_top->next;

    printf("\n Popped value : %d", top->data);
    free(top);
    top = temp_top;

    length--;
}

void traverse_stack()
{
    struct node *temp_top;

    temp_top = top;

    if (temp_top == NULL)
    {
        printf("Stack is empty");
        return;
    }

    while (temp_top != NULL)
    {
        printf("%d ", temp_top->data);
        temp_top = temp_top->next;
    }
}