C语言实现循环队列

SequenceQueue.h

#pragma once

#define ElemType char
#define QuenueSize 5

#define ERROR -1
#define OVERFLOW -2

typedef struct SequenceQueue {
	ElemType* base;
	int front;
	int rear;
	int size;
} Queue;

void InitQueue(Queue& Q);//初始化队列
void DestroyQueue(Queue& Q);//销毁队列
void ClearQueue(Queue& Q);//清空队列
bool EmptyQueue(Queue Q);//判断队列是否为空
ElemType* GetFront(Queue Q);//获取队首元素
void EnQueue(Queue& Q, ElemType e);//入队
void DeQueue(Queue& Q, ElemType& e);//出队
int QueueLength(Queue Q);//获取队列长度
void QueueTraverse(Queue Q, void(*f)(ElemType e));//遍历队列

SequenceQueue.c

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


void InitQueue(Queue& Q) {
	Q.base = (ElemType*)malloc(QuenueSize * sizeof(ElemType));
	if (!Q.base) exit(OVERFLOW);
	Q.size = QuenueSize;
	Q.front = Q.rear = 0;
	printf("init base address:%p,size:%d\n",Q.base,Q.size);
}
void DestroyQueue(Queue& Q) {
	free(Q.base);
	Q.front = Q.rear = 0;
}
void ClearQueue(Queue& Q) {
	Q.front = Q.rear;
}
bool EmptyQueue(Queue Q) {
	return Q.front == Q.rear ? true : false;
}
ElemType* GetFront(Queue Q) {
	return Q.base + Q.front;//从0开始，
}
void EnQueue(Queue& Q, ElemType e) {
	/*
	判断表是否已满
	假设表长度为2，有0，1两个位置
	元素数量	头索引	尾索引
	    1		   0      1
		2		   0	  2%2=0 //此时队列满
		3		   0	  1		//队列溢出

		循环队列需要牺牲一个存储空间来判断队
		队满条件：当队尾指针加1后与队首重合为队满
	*/
	if ((Q.rear + 1) % Q.size == Q.front) exit(OVERFLOW);//溢出退出程序，循环队列扩容比较麻烦，有时间单独研究下
	*(Q.base + Q.rear) = e;
	Q.rear=++Q.rear%Q.size;//队尾指向下次插入的位置
}
void DeQueue(Queue& Q, ElemType& e) {
	if (EmptyQueue(Q)) exit(ERROR);
	e = *(Q.base + Q.front++);
}
int QueueLength(Queue Q) {
	return (Q.rear + Q.size - Q.front) % Q.size;
}
void QueueTraverse(Queue Q, void(*f)(ElemType e)) {
	int cur = Q.front;
	while (cur!=Q.rear)
	{
		f(*(Q.base+cur));
		cur = ++cur % Q.size;
	}
	printf("queue base address:%p,size:%d,queue length:%d\n",Q.base,Q.size,QueueLength(Q));
}

main.c


#include "SequenceQueue.h"

#include <stdio.h>

#include <string.h>



#define EN "en"

#define DE "de"

#define GET "get"

#define EXIT "exit"



void PrintQueue(ElemType e) {

	printf("%c\n", e);

}



int main() {

	char opt[5], e = NULL;

	Queue queue;

	InitQueue(queue);

	while (true)

	{

		gets_s(opt, 5);

		if (strcmp(opt, EN) == 0) {

			printf("wait for input:");

			EnQueue(queue, getchar());

			getchar();

		}

		else if (strcmp(opt, DE) == 0) {

			DeQueue(queue, e);

			printf("DE:%c\n", e);

		}

		else if (strcmp(opt, GET) == 0)

		{
			printf("GET:%c\n", *GetFront(queue));

		}

		else if (strcmp(opt, EXIT) == 0) {

			DestroyQueue(queue);

			break;

		}

		else {

			printf("unkonw operation\n");

			continue;

		}

		printf("queue:\n");

		QueueTraverse(queue, PrintQueue);

	}



}

来源：CSDN

作者：Quarrie

链接：https://blog.csdn.net/Quarrie/article/details/104245412

标签

循环队列