队列（下）之循环队列

循环队列代码

#include <stdio.h>

#include <stdlib.h>

#define MAXSIZE 20

#define OK 1

#define ERROR 0

typedef int data_t;

typedef struct

{

data_t data[MAXSIZE];

int front;//队头位置

int rear;//队尾下一个位置

}SqQueue;

SqQueue *CreateEmptyQueue()//创建队列

{

SqQueue *sq = (SqQueue*)malloc(sizeof(SqQueue));

if(sq==NULL)

{

printf("CreateEmptyQueue Error\n");

return NULL;

}

sq->front=0;

sq->rear=0;

return sq;

}

int DestroyQueue(SqQueue *Q)//销毁队列

{

if(Q==NULL)

{

printf("DestroyQueue Error\n");

return ERROR;

}

free(Q);

Q=NULL;

return OK;

}

int QueueLength(SqQueue *Q)//求当前队列长度

{

return (Q->rear - Q->front + MAXSIZE)%MAXSIZE;

}

int EmptyQueue(SqQueue *Q)//判断队是否为空

{

if(Q==NULL)

{

printf("EmptyQueue Error\n");

return -1;

}

if(Q->rear==Q->front)

return OK;

else

return ERROR;

}

int FullQueue(SqQueue *Q)//判断队是否已满

{

if(Q==NULL)

{

printf("EmptyQueue Error\n");

return -1;

}

if((Q->rear+1)%MAXSIZE==Q->front)

return OK;

else

return ERROR;

}

int EnQueue(SqQueue *Q,data_t e)//元素e入队

{

if(FullQueue(Q)==OK)

{

printf("Queue is Full\n");

return ERROR;

}

Q->data[Q->rear]=e;

Q->rear=(Q->rear+1)%MAXSIZE;

return OK;

}

int DeQueue(SqQueue *Q,data_t *e)//元素出队，出队元素存储在e中

{

if(EmptyQueue(Q)==OK)

{

printf("Queue is Empty\n");

return ERROR;

}

*e=Q->data[Q->front];

Q->front=(Q->front+1)%MAXSIZE;

return OK;

}

int main()

{

/*

SqQueue *queue = CreateEmptyQueue();

data_t data;

EnQueue(queue,20);

EnQueue(queue,30);

EnQueue(queue,40);

DeQueue(queue,&data);

printf("DeQueue:%d\n",data);

DeQueue(queue,&data);

printf("DeQueue:%d\n",data);

DeQueue(queue,&data);

printf("DeQueue:%d\n",data);

DeQueue(queue,&data);

printf("DeQueue:%d\n",data);//此处应输出1个“队列为空”

for(data=0;data<25;data++)//此处应输出6个“队列已满”

{

EnQueue(queue,data);

}

if(DestroyQueue(queue)==OK)

printf("DestroyQueue success\n");

return 0;

*/

}