循环队列

// test_demo.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include "stdio.h"#include "windows.h"#define QueueSize 100 /*假定预分配的队列空间最多为100个元素*/  typedef int DataType; /*假定队列元素的数据类型为字符*/  typedef struct{DataType data[QueueSize];int front; /*头指针*/int rear;  /*尾指针*/int count; /*计数器，记录队中元素总数*/           }CirQueue;   /* 置队列空*/void Initial(CirQueue *Q){/*将顺序队列置空*/Q->front=Q->rear=0;Q->count=0;     /*计数器置0*/       } /* 判队列空*/int IsEmpty(CirQueue *Q){return Q->front==Q->rear;}/*判队列满*/int IsFull(CirQueue *Q){return Q->rear==QueueSize-1+Q->front;}/*进队列*/void EnQueue(CirQueue *Q,DataType x){if (IsFull(Q)){printf("队列上溢"); /*上溢,退出运行*/exit(1);}Q->count ++;                        /*队列元素个数加1*/Q->data[Q->rear]=x;                 /*新元素插入队尾*/Q->rear=(Q->rear+1)%QueueSize;      /*循环意义下将尾指针加1*/}/*出队列*/DataType DeQueue(CirQueue *Q){DataType temp;if(IsEmpty(Q)){printf("队列为空"); /*下溢,退出运行*/exit(1);}temp=Q->data[Q->front];Q->count--;                        /*队列元素个数减1*/Q->front=(Q->front+1)&QueueSize;   /*循环意义下的头指针加1*/return temp; }/* 取队列顶元素*/DataType Front(CirQueue *Q){if(IsEmpty(Q)){printf("队列为空"); /*下溢,退出运行*/exit(1);}printf("Q->data[Q->front]:%c\n",Q->data[Q->front]);return Q->data[Q->front];}int _tmain(int argc, _TCHAR* argv[]){CirQueue s;DataType first,sec;Initial(&s);EnQueue(&s,'a');EnQueue(&s,'b');first=Front(&s);DeQueue(&s);sec=Front(&s);DeQueue(&s);while(1);return 0;}