我要成为嵌入式高手之3月22日数据结构第五天！！
————————————————————————————

顺序队列

存在问题：假溢出——解决办法：循环队列

空队列、满队列如何判断？

满队列：rear + 1 = front

空队列：rear = front

循环队列

相当于数组

由于有一个指针始终要进行判断队列，所以只有n-1个数据

1、创建

SEQ_QUE *CreateSqeQueue(int max)
{
    SEQ_QUE *pseq = malloc(sizeof(SEQ_QUE));
    if (NULL == pseq)
    {
        perror("fail to malloc");
        return NULL;
    }

    pseq->pbase = malloc(max*sizeof(DATA_TYPE));
    if (NULL == pseq->pbase)
    {
        perror("fail to malloc");
        return NULL;
    }

    pseq->front = 0;
    pseq->rear = 0;
    pseq->size = max;

    return pseq;
}

2、判断是否为满队列

/* 满队列 */
int FullOfSeq(SEQ_QUE *pseq)
{
    if ((pseq->rear+1) % pseq->size == pseq->front)//尾的下一个是头
    {
        return 1;
    }
    return 0;
}

3、判断是否为空队列

/* 空队列 */
int EmptyOfSeq(SEQ_QUE *pseq)
{
    if (pseq->front == pseq->rear)//头和尾相同
    {
        return 1;
    }
    return 0;
}

4、入队

int JoinInSeq(SEQ_QUE *pseq, DATA_TYPE data)
{
    if (FullOfSeq(pseq))
    {
        return -1;
    }

    pseq->pbase[pseq->rear] = data;
    pseq->rear = (pseq->rear+1) % pseq->size;

    return 0;
}

5、遍历

int SearchQueAll(SEQ_QUE *pseq)
{
    int i = pseq->front;
    while (i != pseq->rear)
    {
        printf("%d ", pseq->pbase[i]);
        i = (i+1) % pseq->size;
    }
    putchar('\n');

    return 0;
}

6、出队

int PopInSeq(SEQ_QUE *pseq, DATA_TYPE *pdata)
{
    if (EmptyOfSeq(pseq))
    {
        return -1;
    }

    if (pdata != NULL)
    {
        *pdata = pseq->pbase[pseq->front];
    }

    pseq->front = (pseq->front+1) % pseq->size;

    return 0;
}

7、清空队列

void ClearSeq(SEQ_QUE *pseq)
{
    pseq->front = pseq->rear = 0;
}
//头和尾相同且为0，意为清空队列

8、销毁队列

void DestroySeq(SEQ_QUE *pseq)
{
    free(pseq->pbase);
    free(pseq);
}

总程序：

head.h

#ifndef _HEAD_H
#define _HEAD_H

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

typedef int DATA_TYPE;

typedef struct que
{
    DATA_TYPE *pbase;
    int front;
    int rear;
    int size;
}SEQ_QUE;

extern SEQ_QUE *CreateSqeQueue(int max);
extern int JoinInSeq(SEQ_QUE *pseq, DATA_TYPE data);
extern int SearchQueAll(SEQ_QUE *pseq);
extern int PopInSeq(SEQ_QUE *pseq, DATA_TYPE *pdata);
extern void ClearSeq(SEQ_QUE *pseq);
extern void DestroySeq(SEQ_QUE *pseq);

#endif

queue.c

#include "head.h"

SEQ_QUE *CreateSqeQueue(int max)
{
    SEQ_QUE *pseq = malloc(sizeof(SEQ_QUE));
    if (NULL == pseq)
    {
        perror("fail to malloc");
        return NULL;
    }

    pseq->pbase = malloc(max*sizeof(DATA_TYPE));
    if (NULL == pseq->pbase)
    {
        perror("fail to malloc");
        return NULL;
    }

    pseq->front = 0;
    pseq->rear = 0;
    pseq->size = max;

    return pseq;
}

/* 满队列 */
int FullOfSeq(SEQ_QUE *pseq)
{
    if ((pseq->rear+1) % pseq->size == pseq->front)//尾的下一个是头
    {
        return 1;
    }
    return 0;
}

/* 空队列 */
int EmptyOfSeq(SEQ_QUE *pseq)
{
    if (pseq->front == pseq->rear)//头和尾相同
    {
        return 1;
    }
    return 0;
}

int JoinInSeq(SEQ_QUE *pseq, DATA_TYPE data)
{
    if (FullOfSeq(pseq))
    {
        return -1;
    }

    pseq->pbase[pseq->rear] = data;
    pseq->rear = (pseq->rear+1) % pseq->size;

    return 0;
}

int SearchQueAll(SEQ_QUE *pseq)
{
    int i = pseq->front;
    while (i != pseq->rear)
    {
        printf("%d ", pseq->pbase[i]);
        i = (i+1) % pseq->size;
    }
    putchar('\n');

    return 0;
}

int PopInSeq(SEQ_QUE *pseq, DATA_TYPE *pdata)
{
    if (EmptyOfSeq(pseq))
    {
        return -1;
    }

    if (pdata != NULL)
    {
        *pdata = pseq->pbase[pseq->front];
    }

    pseq->front = (pseq->front+1) % pseq->size;

    return 0;
}

void ClearSeq(SEQ_QUE *pseq)
{
    pseq->front = pseq->rear = 0;
}

void DestroySeq(SEQ_QUE *pseq)
{
    free(pseq->pbase);
    free(pseq);
}

 main.c

#include "head.h"

int main(void)
{
    DATA_TYPE data;
    SEQ_QUE *pseq = CreateSqeQueue(2);
    if (NULL == pseq)
    {
        perror("fail to create!");
        return -1;
    }
    JoinInSeq(pseq, 1);
    JoinInSeq(pseq, 2);
    JoinInSeq(pseq, 3);
    SearchQueAll(pseq);
    
    

    return 0;
}