Queue implementation using linked list in C.

LinkedListQueue.c

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

struct Node {
    int key;
    Node * next;
};

struct Queue {
    Node * head;
    Node * tail;
};

typedef struct Node Node;
typedef struct Queue Queue;

Queue * create_queue(void);
unsigned is_empty(Queue *);
int get_head(Queue *);
void enqueue(Queue *, int);
void dequeue(Queue *);

Queue * create_queue() {
    Queue * qu = malloc(sizeof(Queue));
    qu -> head = NULL;
    qu -> tail = NULL;
    return qu;
}

unsigned is_empty(Queue * qu) {
    return qu -> head == NULL && qu -> tail == NULL;
}

int get_head(Queue * qu) {
    assert(!is_empty(qu));
    return qu -> head -> key;
}

void enqueue(Queue * qu, int key) {
    Node * nd = malloc(sizeof(Node));
    nd -> key = key;
    nd -> next = NULL;
    if (is_empty(qu)) {
        qu -> head = nd;
        qu -> tail = nd;
    } else {
        qu -> tail -> next = nd;
        qu -> tail = nd;
    }
}

void dequeue(Queue * qu) {
    assert(!is_empty(qu));
    Node * tmp_node = qu -> head;
    qu -> head = tmp_node -> next;
    free(tmp_node);
    if (qu -> head == NULL) 
        qu -> tail = NULL;
}