数据结构3.7--循环队列

1.循环队列代码实现

代码如下（示例）：

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

#define TOTAL_SPACE 5

typedef struct CircleIntQueue {
	int data[TOTAL_SPACE];

	int front;

	int rear;
}*CircleIntQueuePtr;

CircleIntQueuePtr initQueue() {
	CircleIntQueuePtr resultPtr = (CircleIntQueuePtr)malloc(sizeof(struct CircleIntQueue));
	resultPtr->front = 0;
	resultPtr->rear = 0;

	return resultPtr;
}

void enqueue(CircleIntQueuePtr paraPtr, int paraValue) {
	printf("Enqueue: %d ", paraValue);
	if ((paraPtr->rear + 1) % TOTAL_SPACE == paraPtr->front) {
		printf("Queue full.\r\n");
		return;
	}

	paraPtr->data[paraPtr->rear] = paraValue;
	paraPtr->rear = (paraPtr->rear + 1) % TOTAL_SPACE;
}

int dequeue(CircleIntQueuePtr paraPtr) {
	int resultValue;
	if (paraPtr->front == paraPtr->rear) {
		printf("No element in the queue.\r\n");
		return -1;
	}

	resultValue = paraPtr->data[paraPtr->front];
	paraPtr->front = (paraPtr->front + 1) % TOTAL_SPACE;

	return resultValue;
}

void outputCircleIntQueue(CircleIntQueuePtr paraPtr) {
	int i;
	if (paraPtr->front == paraPtr->rear) {
		printf("Empty queue.");
		return;
	}

	printf("Elements in the queue:");
	for (i = paraPtr->front; i != paraPtr->rear; i = (i + 1) % TOTAL_SPACE) {
		printf("data[%d] = %d, ", i, paraPtr->data[i]);
	}

	printf("\r\n");
}

void testCircleIntQueue() {
	int i = 10;
	CircleIntQueuePtr tempPtr = initQueue();
	for (; i < 16; i++) {
		enqueue(tempPtr, i);
	}

	outputCircleIntQueue(tempPtr);

	for (i = 0; i < 6; i++) {
		printf("dequeue gets %d\r\n", dequeue(tempPtr));
	}

	for (i = 3; i < 6; i++) {
		enqueue(tempPtr, i);
	}

	for (i = 20; i < 30; i++) {
		enqueue(tempPtr, i);
		printf("dequeue gets %d\r\n", dequeue(tempPtr));
		outputCircleIntQueue(tempPtr);
	}

}

int main() {
	testCircleIntQueue();
	return 1;
}

2.输出结果

代码如下（示例）：

Enqueue: 10 Enqueue: 11 Enqueue: 12 Enqueue: 13 Enqueue: 14 Queue full.
Enqueue: 15 Queue full.
Elements in the queue:data[0] = 10, data[1] = 11, data[2] = 12, data[3] = 13,
dequeue gets 10
dequeue gets 11
dequeue gets 12
dequeue gets 13
No element in the queue.
dequeue gets -1
No element in the queue.
dequeue gets -1
Enqueue: 3 Enqueue: 4 Enqueue: 5 Enqueue: 20 dequeue gets 3
Elements in the queue:data[0] = 4, data[1] = 5, data[2] = 20,
Enqueue: 21 dequeue gets 4
Elements in the queue:data[1] = 5, data[2] = 20, data[3] = 21,
Enqueue: 22 dequeue gets 5
Elements in the queue:data[2] = 20, data[3] = 21, data[4] = 22,
Enqueue: 23 dequeue gets 20
Elements in the queue:data[3] = 21, data[4] = 22, data[0] = 23,
Enqueue: 24 dequeue gets 21
Elements in the queue:data[4] = 22, data[0] = 23, data[1] = 24,
Enqueue: 25 dequeue gets 22
Elements in the queue:data[0] = 23, data[1] = 24, data[2] = 25,
Enqueue: 26 dequeue gets 23
Elements in the queue:data[1] = 24, data[2] = 25, data[3] = 26,
Enqueue: 27 dequeue gets 24
Elements in the queue:data[2] = 25, data[3] = 26, data[4] = 27,
Enqueue: 28 dequeue gets 25
Elements in the queue:data[3] = 26, data[4] = 27, data[0] = 28,
Enqueue: 29 dequeue gets 26
Elements in the queue:data[4] = 27, data[0] = 28, data[1] = 29,