循环队列的程序

#include <stdio.h>
#define MAX 10
#define TRUE 1

typedef struct
{
  int data[MAX];
  int front, rear;
  int isNull;
}Sequeue;

void Init(Sequeue *sq)
{
  sq->front=0;
  sq->rear=0;
  sq->isNull=1;
}

int Ins(Sequeue *sq,int x)
{
   if((sq->front+1)%MAX ==(sq->rear+1)%MAX && sq->isNull!=1)
   {
     printf("\nFull squeue!New data in the old position!\n");

     sq->rear=(sq->rear+1)%MAX;
     sq->data[sq->rear]=x;
     sq->front=(sq->front+1)%MAX;
   }
   else
   {
     sq->rear=(sq->rear+1)%MAX;
     sq->data[sq->rear]=x;
     printf("\nData in\n");
  sq->isNull=0;
     return(TRUE);
   }

   sq->isNull=0;
   return x;
}

int Del(Sequeue *sq,int x)
{
   if(sq->rear==sq->front && sq->isNull==1)
   {
    printf("the queue is empty\n");
    return NULL;
   }
   else
   {
    if((sq->rear)%MAX==(sq->front+1)%MAX)
  sq->isNull=1;
 sq->front=(sq->front+1)%MAX;
    x= sq->data[sq->front];
    printf("\nData out\n");
    return(x);
   }
}

int Print(Sequeue *sq)
{
   int k;

   if(sq->rear==sq->front && sq->isNull==1)
   {
    printf("the queue is empty\n");
    return NULL;
   }
   else
   printf("The sequeue is:\n");

    k=sq->front;
    do
    {
     k++;
     k=k%MAX;
     printf("-%d-",sq->data[k]);
    }while(k!=sq->rear);
  return 1;
}

main()
{

  Sequeue *head=(Sequeue*)malloc(sizeof(Sequeue));
  int c,x;

  clrscr();
  Init(head);
  
  do
  {
   printf("\n**********\nPlease select a number to input:\n1 insert a number\n2 delete a number\n3 print the squeue\n4 quit the program\n**********\n");
   c=getch();
   switch(c)
   {    case'1':
              printf("\nPlease Enter a number\n");
              scanf("%d",&x);
              Ins(head,x);
              break;

       case '2':
              Del(head,x);
              break;
       case'3':
              Print(head);
              break;
   }
  }while(c!='4');
  free(head);
 
}