C语言队列_initializequeue

 队列为先进先出。实例：手机应用商店应用更新队列，但这个可以强制调换队列顺序。

代码注释已经很详细了，不在解释。

Queue.h

#ifndef _QUEUE_H_
#define _QUEUE_H_
#include <stdbool.h>
 
typedef int Item;
 
#define MAXQUEUE 10
 
typedef struct node
{
	Item item;
	struct node* next; 
}Node;
 
typedef struct queue
{
	Node* front;       //记录头部
	Node* rear;        //记录尾部
	int items;         //记录项数
}Queue;
 
//队列初始化为空
void InitializeQueue(Queue* pq);
 
//检查队列是否以满
bool QueueIsFull(const Queue* pq);
 
//检查队列是否为空
bool QueueIsEmtpy(const Queue* pq);
 
//确定队列中的项数
int QueueItemCount(const Queue* pq);
 
//在队列末尾添加项
bool EnQueue(Item item, Queue* pq);
 
//从队列的开头删除项
bool DeQueue(Item* pitem, Queue* pq);
 
//清空队列
void EmptyTheQueue(Queue* pq);
 
#endif

Queue.cpp

#include <stdio.h>
#include <stdlib.h>
#include "queue.h"
 
static void CopyToNode(Item item, Node* pn);
static void CopyToItem(Node* pn, Item* pi);
 
void InitializeQueue(Queue* pq)   //初始化
{
	pq->front = NULL;
	pq->rear = NULL;
	pq->items = 0;
}
 
bool QueueIsFull(const Queue* pq)  //判断是否已满  10
{
	return pq->items == MAXQUEUE;
}
 
bool QueueIsEmtpy(const Queue* pq)  //检查队列是否为空
{
	return pq->items == 0;
}
 
int QueueItemCount(const Queue* pq)  //确定队列中的项数
{
	return pq->items;
}
 
bool EnQueue(Item item, Queue* pq)  //在末尾添加项  item=1;
{
	Node* pnew = {};
 
	if (QueueIsFull(pq))
		return false;
	pnew = (Node*)malloc(sizeof(Node));
	if (pnew == NULL)
	{
		fprintf(stderr, "Unable to allocate memory!\n");
		exit(1);
	}
 
	CopyToNode(item, pnew);
	pnew->next == NULL;
	if (QueueIsEmtpy(pq))
	{
		pq->front = pnew;
	}
	else
	{
		pq->rear->next = pnew;      
	}
	pq->rear = pnew;              
	pq->items++;
 
	return true;
}
 
bool DeQueue(Item* pitem, Queue* pq)  //从队列开头删除项
{
	Node* pt = {};
 
	if (QueueIsEmtpy(pq))
		return false;
 
	CopyToItem(pq->front, pitem);
	pt = pq->front;
	pq->front = pq->front->next;
	free(pt);
 
	pq->items--;
	if (pq->items == 0)
		pq->rear = NULL;
 
	return true;
}
 
void EmptyTheQueue(Queue* pq)      //清空队列
{
	Item dummy;
	while (!QueueIsEmtpy(pq))
		DeQueue(&dummy, pq);
}
 
void CopyToNode(Item item, Node* pn)  //拷贝到节点
{
	pn->item = item;
}
 
void CopyToItem(Node* pn, Item* pi)    //拷贝到项目
{
	*pi = pn->item;
}

UseQueue.cpp

#include <stdio.h>
#include "queue.h"
 
int main(void)
{
	char ch;
	Item temp;
	Queue line;
 
	InitializeQueue(&line);
	puts("Testing the Queue interface. Type a to add a value,");
	puts("type d to delete a value, and type q to quit.");
 
	while ((ch = getchar()) != 'q')
	{
		if (ch != 'a' && ch != 'd')
		{
			printf("incorrect input\n");
			continue;
		}
			
		if (ch == 'a')
		{
			printf("Integer to add: ");
			scanf_s("%d", &temp);
 
			if (!QueueIsFull(&line))
			{
				printf("Putting %d into queue\n", temp);
				EnQueue(temp, &line);
			}
			else
				puts("Queue is full!");
		}
		else
		{
			if (QueueIsEmtpy(&line))
				puts("Noting to delete!");
			else
			{
				DeQueue(&temp, &line);
				printf("Removing %d from queue\n", temp);
			}
		}
		printf("%d items in queue\n", QueueItemCount(&line));
		puts("Type a to add, d to delete, q to quit:");
	}
 
	EmptyTheQueue(&line);
	puts("bye!");
 
	return 0;
}

运行结果

 Success is going from failure to failure without losing enthusiasm.

成功是从一次失败走向另一次失败，却不失热情。