循环队列的基本操作

头文件：SqQueue.h

#include<cstdlib>
#include<iostream>
using namespace std;
#define MAXQSIZE 100
#define TRUE 1
#define FALSE 0
#define OK 1
#define ERROR 0
#define INFEASIBLE -1
typedef int QElemType;
typedef int Status;

typedef struct
{
 QElemType *base;
 int front;
 int rear;
}SqQueue;

//构造一个空队列
Status InitQueue(SqQueue& Q)
{
 Q.base = (QElemType*)malloc(MAXQSIZE*sizeof(QElemType));
 if (!Q.base)
  exit(OVERFLOW);
 Q.front = Q.rear = 0;
 return OK;
}

//销毁队列Q
Status DestroyQueue(SqQueue& Q)
{
 if (Q.base)
 {
  free(Q.base);
  Q.base = NULL;
  Q.front = Q.rear = 0;
 }
 return OK;
}

//清空队列Q
Status ClearQueue(SqQueue& Q)
{
 Q.front = Q.rear = 0;
 return OK;
}

//若队列Q为空，则返回TRUE;否则返回FALSE
Status QueueEmpty(SqQueue Q)
{
 if (Q.front == Q.rear)
  return TRUE;
 else
  return FALSE;
}

//返回Q的元素个数
int QueueLength(SqQueue Q)
{
 return (Q.rear - Q.front + MAXQSIZE) % MAXQSIZE;
}

//若队列不空，则用e返回队列Q的队头元素，并返回OK;否则返回ERROR
Status GetHead(SqQueue Q, QElemType& e)
{
 if (!QueueEmpty(Q))
 {
  e = Q.base[Q.front];
  return OK;
 }
 return ERROR;
}

//插入元素e为Q新的队尾元素
Status EnQueue(SqQueue& Q, QElemType e)
{
 if ((Q.rear + 1) % MAXQSIZE == Q.front)
  return ERROR;
 Q.base[Q.rear] = e;
 Q.rear = (Q.rear + 1) % MAXQSIZE;
 return OK;
}

//若队列不空，则删除Q的队头元素，用e返回其值，并返回OK;否则返回ERROR
Status DeQueue(SqQueue& Q, QElemType& e)
{
 if (Q.front == Q.rear)
  return ERROR;
 e = Q.base[Q.front];
 Q.front = (Q.front + 1) % MAXQSIZE;
 return OK;
}

//打印输出队列的元素
Status visit(QElemType data)
{
 if (cout << data << "  ")
  return OK;
 else
  return ERROR;
}

//依次对队列Q的元素调用函数visit().一旦调用visit()失败，则操作失败
Status QueueTraverse(SqQueue Q, Status(*visit)(QElemType))
{
 int k = Q.front;
 for (int i = 1; i <= QueueLength(Q); ++i)
 {
  if (!(*visit)(Q.base[k]))
   return ERROR;
  k = (k + 1) % MAXQSIZE;
 }
 cout << endl;
 return OK;
}

主程序：

#include"SqQueue.h"
void main(void)
{
 SqQueue Q;
 InitQueue(Q);
 for (int i = 1; i < 20; i += 2)
  EnQueue(Q, i);
 cout << "队列Q的基本信息：" << endl;
 QueueTraverse(Q, visit);
 cout << "Q的长度为:" << QueueLength(Q) << endl;
 cout << "Q的队头元素为:";
 QElemType e;
 GetHead(Q, e);
 cout << e << endl;
 cout << "Q是否为空：";
 if (!QueueEmpty(Q))
 {
  cout << "否！" << endl;
  int i = 1;
  while (i <= QueueLength(Q))
  {
   DeQueue(Q, e);
   ++i;
  }
 }
 else
  cout << "是！";
 DestroyQueue(Q);
}