queue implementation in C.

Queue.c

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

struct Queue {
    int * keys;
    int head;
    int tail;
    int max_size;
};

typedef struct Queue Queue;

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


Queue * create_queue(int max_size) {
    Queue * qu = malloc(sizeof(Queue));
    qu -> keys = malloc(max_size * sizeof(int));
    qu -> head = 0;
    qu -> tail = 0;
    qu -> max_size = max_size;
    return qu;
}

unsigned is_empty(Queue qu) {
    return qu.head == qu.tail;
}

int get_head(Queue qu) {
    assert(!is_empty(qu));
    int index = qu.head + 1;
    if (index > qu.max_size - 1) 
        index = 0;
    return qu.keys[qu.head];
}

void enqueue(Queue * qu, int key) {
    qu -> tail++;
    if (qu -> tail > qu -> max_size - 1) 
        qu -> tail = 0;
    assert(!is_empty(*qu));
    qu -> keys[qu -> tail] = key;
}

void dequeue(Queue * qu) {
    assert(!is_empty(*qu));
    qu -> head++;
    if (qu -> head > qu -> max_size - 1)
        qu -> head = 0;
}