编写可伸缩循环队列的源代码，并保存为一个或多个源文件

好的，以下是一个可伸缩循环队列的源代码，分为头文件和实现文件两部分：

**queue.h**

#ifndef QUEUE_H
#define QUEUE_H

#include <stddef.h>

typedef struct {
    void** data;
    size_t front;
    size_t rear;
    size_t capacity;
} Queue;

Queue* queue_create(size_t capacity);
void queue_destroy(Queue* queue);
int queue_is_empty(Queue* queue);
int queue_is_full(Queue* queue);
int queue_enqueue(Queue* queue, void* element);
void* queue_dequeue(Queue* queue);

#endif

**queue.c**

#include <stdlib.h>
#include "queue.h"

#define INITIAL_CAPACITY 10

Queue* queue_create(size_t capacity) {
    Queue* queue = (Queue*)malloc(sizeof(Queue));
    if (queue == NULL) {
        return NULL;
    }

    queue->data = (void**)malloc(sizeof(void*) * capacity);
    if (queue->data == NULL) {
        free(queue);
        return NULL;
    }

    queue->front = 0;
    queue->rear = 0;
    queue->capacity = capacity;

    return queue;
}

void queue_destroy(Queue* queue) {
    free(queue->data);
    free(queue);
}

int queue_is_empty(Queue* queue) {
    return queue->front == queue->rear;
}

int queue_is_full(Queue* queue) {
    return (queue->rear + 1) % queue->capacity == queue->front;
}

int queue_enqueue(Queue* queue, void* element) {
    if (queue_is_full(queue)) {
        void** new_data = (void**)malloc(sizeof(void*) * queue->capacity * 2);
        if (new_data == NULL) {
            return 0;
        }

        size_t i, j;
        for (i = queue->front, j = 0; i != queue->rear; i = (i + 1) % queue->capacity, j++) {
            new_data[j] = queue->data[i];
        }

        free(queue->data);
        queue->data = new_data;
        queue->front = 0;
        queue->rear = j;
        queue->capacity *= 2;
    }

    queue->data[queue->rear] = element;
    queue->rear = (queue->rear + 1) % queue->capacity;

    return 1;
}

void* queue_dequeue(Queue* queue) {
    if (queue_is_empty(queue)) {
        return NULL;
    }

    void* element = queue->data[queue->front];
    queue->front = (queue->front + 1) % queue->capacity;

    return element;
}

这个队列可以动态地增加容量，因此可以根据需要存储任意数量的元素。