链队列和循环队列（c语言数据结构）

一、链队列：
链队是指采用链式存储结果实现的队列，通常用单链表来表示。一个链队需要两个分别指示队头和队尾的指针才能确定。

代码：

#include 
#include 

//链队列的节点 
typedef struct LinkNode{
	int data;
	LinkNode* next;
}*LinkNodePtr;

//链队列.
typedef struct LinkQueue{
	LinkNodePtr front;
	LinkNodePtr rear;
}*LinkQueuePtr;

//初始化 
LinkQueuePtr initQueue(){
	LinkQueuePtr resultPtr = (LinkQueuePtr)malloc(sizeof(struct LinkQueue));
	
	LinkNodePtr headerPtr = (LinkNodePtr)malloc(sizeof(LinkNodePtr));
	headerPtr->next = NULL;
	
	resultPtr->front = headerPtr;
	resultPtr->rear = headerPtr;
	return resultPtr;
}

//输出队列元素 
void outputLinkQueue(LinkQueuePtr paraQueuePtr){
	LinkNodePtr tempPtr = paraQueuePtr->front->next;
	while (tempPtr != NULL) {
		printf("%d ", tempPtr->data);
		tempPtr = tempPtr->next;
	}
	printf("rn");
}

//入队 
void enqueue(LinkQueuePtr paraQueuePtr, int paraElement) {
	//创建一个新节点
	LinkNodePtr tempNodePtr = (LinkNodePtr)malloc(sizeof(struct LinkNode));
	tempNodePtr->data = paraElement;
	tempNodePtr->next = NULL;
	
	//将该节点与链表连接 
	paraQueuePtr->rear->next = tempNodePtr;
	
	//尾指针指向新的尾结点 
	paraQueuePtr->rear = tempNodePtr;
}

//出队 
int dequeue(LinkQueuePtr paraQueuePtr) {
	int resultValue;
	LinkNodePtr tempNodePtr;

	//判断队列是否为空 
	if (paraQueuePtr->front == paraQueuePtr->rear) {
		printf("队列为空！n");
		return -1;
	}
	
	tempNodePtr = paraQueuePtr->front->next;
	resultValue = tempNodePtr->data;
	paraQueuePtr->front->next = paraQueuePtr->front->next->next;

	if (paraQueuePtr->rear == tempNodePtr) {
		paraQueuePtr->rear = paraQueuePtr->front;
	}
	
	//free()
	tempNodePtr = NULL;

	return resultValue;
}
	
//功能测试 
void testLinkQueue(){
	LinkQueuePtr tempQueuePtr;
	tempQueuePtr = initQueue();
	enqueue(tempQueuePtr, 10);
	enqueue(tempQueuePtr, 30);
	enqueue(tempQueuePtr, 50);
	enqueue(tempQueuePtr, 80);

	outputLinkQueue(tempQueuePtr);

	printf("dequeue gets %drn", dequeue(tempQueuePtr));
	printf("dequeue gets %drn", dequeue(tempQueuePtr));
	printf("dequeue gets %drn", dequeue(tempQueuePtr));
	printf("dequeue gets %drn", dequeue(tempQueuePtr));
	printf("dequeue gets %drn", dequeue(tempQueuePtr));
	printf("dequeue gets %drn", dequeue(tempQueuePtr));
	
	enqueue(tempQueuePtr, 8);
	outputLinkQueue(tempQueuePtr);
}
 
//main函数 
int main(){
	testLinkQueue();
	return 1;
}

运行结果：

10 30 50 80
dequeue gets 10
dequeue gets 30
dequeue gets 50
dequeue gets 80
队列为空！
dequeue gets -1
队列为空！
dequeue gets -1
8

二、循环队列

在循环队列中判断队空队满的条件：
队空的条件：Q.front = Q.rear
队满的条件：（Q.rear+1）%MAQSIZE == Q.front

代码：

#include 
#include 

#define MAXSIZE 5

typedef struct CircleIntQueue{
	int data[MAXSIZE];
	int front;
	int rear;
}*CircleIntQueuePtr;

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

	return resultPtr;
}

//入队 
void enqueue(CircleIntQueuePtr paraPtr, int paraValue) {
	if ((paraPtr->rear + 1) % MAXSIZE == paraPtr->front) {
		printf("Queue full.rn");
		return;
	}

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

//出队 
int dequeue(CircleIntQueuePtr paraPtr) {
	int resultValue;
	if (paraPtr->front == paraPtr->rear) {
		printf("Queue is empty.rn");
		return -1;
	} 
	
	resultValue = paraPtr->data[paraPtr->front % MAXSIZE];
	paraPtr->front = (paraPtr->front+1) % MAXSIZE;
	
	return resultValue;
}

//打印 
void outputLinkQueue(CircleIntQueuePtr paraPtr)
{
    //当队头指针和队尾指针相等时队为空
    for(int i = paraPtr->front; i != paraPtr->rear; i = (i + 1) % MAXSIZE)
    {
        printf("data[%d] = %d ",i,paraPtr->data[i]);
    }
    printf("n");
}


//功能测试 
void testLinkQueue(){
	int i = 10;
	CircleIntQueuePtr tempPtr = initQueue();
	for (; i < 16; i ++) {
		enqueue(tempPtr, i);
	}

	outputLinkQueue(tempPtr);

	for (i = 0; i < 6; i ++) {
		printf("dequeue gets %drn", dequeue(tempPtr));
	}

	enqueue(tempPtr, 8);
	enqueue(tempPtr, -10);
	enqueue(tempPtr, 15);
	outputLinkQueue(tempPtr);
}
 
int main()
{
	testLinkQueue();
	return 0;
}

运行结果：

Queue full.
Queue full.
data[0] = 10 data[1] = 11 data[2] = 12 data[3] = 13
dequeue gets 10
dequeue gets 11
dequeue gets 12
dequeue gets 13
Queue is empty.
dequeue gets -1
Queue is empty.
dequeue gets -1
data[4] = 8 data[0] = -10 data[1] = 15