双链表（C实现）

输出限制性双队列

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

typedef struct _queue
{
	int data;
	struct _queue *next;
}QUEUE;

QUEUE * rear = NULL;
QUEUE * front = NULL;

//输出限制性双队列
int OutQueue(int *value)
{
	QUEUE * p = NULL;
	if(front == NULL)
		return 0;
	p = front;
	front = front->next;
	*value = p->data;
	free(p);
	return 1;
}

int InQueueByRear(int value)
{
	QUEUE *q = (QUEUE *)malloc(sizeof(QUEUE));
	if(q == NULL)	return 0;
	q->data = value;
	q->next = NULL;
	if(rear == NULL)
		front = q;
	else
		rear->next = q;
	rear = q;
	return 1;
}

int InQueueByFront(int value)
{
	QUEUE *q = (QUEUE *)malloc(sizeof(QUEUE));
	if(q == NULL) return 0;
	q->data = value;
	q->next = front;
	front = q;
	if(rear == NULL)
		rear = q;
	return 1;
}

void PrintQueue()
{
	QUEUE *p = front;
	while(p)
	{
		printf("%5d",p->data);
		p = p->next;
	}
	printf("\n");
}

void main()
{
	int res;
	while(1)
	{
		printf("1：从队头存入；2：从队尾存入；3：退出=》");
		scanf("%d",&res);
		fflush(stdin);
		if(res == 1)
		{
			printf("请输入要存入的值：");
			scanf("%d",&res);
			fflush(stdin);
			if(InQueueByFront(res))
			{
				PrintQueue();
			}else
				printf("存入失败");
		}else if(res == 2)
		{
			printf("请输入要存入的值：");
			scanf("%d",&res);
			fflush(stdin);
			if(InQueueByRear(res))
			{
				PrintQueue();
			}else
				printf("存入失败");
		}else if(res == 3)
			break;
	}
}

VC6运行效果图

输入限制性双队列

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

typedef struct _queue
{
	int data;
	struct _queue *next;
}QUEUE;

QUEUE * rear = NULL;
QUEUE * front = NULL;

//输入限制性双队列
int InQueue(int value)
{
	QUEUE * q = (QUEUE *)malloc(sizeof(QUEUE));
	if(q == NULL) return 0;
	q -> data = value;
	q -> next = NULL;
	if(front == NULL)
		front = q;
	else
		rear ->next = q;
	rear = q;
	return 1;
}

int OutQueueByFront(int *value)
{
	QUEUE * p = NULL;
	if(front == NULL)
		return 0;
	p = front;
	front = front->next;
	*value = p->data;
	free(p);
	return 1;
}

int OutQueueByRear(int *value)
{
	QUEUE *p = NULL;
	if(rear == NULL)
		return 0;
	if(rear == front)
	{
		*value = rear->data;
		free(rear);
		rear = NULL;
		front = NULL;
	}else
	{
		p = front;
		while(p->next != rear)
			p = p->next;
		*value = rear->data;
		free(rear);
		rear = p;
		rear->next = NULL;
	}
	return 1;
}

void main()
{
	int res,i,arr[5]={1,2,3,4,5};
	for(i = 0;i < 5;i ++)
		InQueue(arr[i]);
	while(1)
	{
		printf("1：从队头取出；2：从队尾取出；3：退出=》");
		scanf("%d",&res);
		fflush(stdin);
		if(res == 1)
		{
			if(OutQueueByFront(&res) == 1)
				printf("取出的值为：%d\n",res);
			else
				printf("队列为空！\n");
		}else if(res == 2)
		{
			if(OutQueueByRear(&res) == 1)
				printf("取出的值为：%d\n",res);
			else
				printf("队列为空！\n");
		}else if(res == 3)
			break;
	}
}

VC6运行效果图