queue.c

queue这是一个如何制作一个queue的程式

           #include <stdio.h>
           #include <stdlib.h>
           #define NUM 100
           typedef struct queue
           {
            int q[NUM];
            int rear;
            int front;        
           }Queue;
           Queue qu;
           void printQueue(void);
           void enqueue(int);
           int dequeue(void);
           int main(void)
           {
            int choice=0,n;
            qu.rear=-1;
            qu.front=-1;
            while(choice!=-1)
            {
             printf("1)enqueue 2)dequeue 3) print current queue\n");
             printf("enter your choice");
             scanf("%d",&choice);
             switch(choice)
             {
              case 1: printf("what do you want to enqueue?");
                      scanf("%d",&n);
                      enqueue(n);
                      break;
              case 2:n=dequeue();
                     if(n!=-1)
                     printf("%d was dequeued from queue\n",n);
                     break;
              case 3:printQueue();
                     break;
              }
            }
            system("pause");
            return 0;
     }
       void enqueue(int n)
       {
        if(qu.rear==NUM-1)
        {
         fprintf(stderr,"queue is full!\n");
         return;                  
        }else
        qu.q[++qu.rear]=n;
}       
int dequeue(void)
{
 if(qu.front==qu.rear)
  {
   fprintf(stderr,"queue is empty!\n");
   return -1;
  }
  else
   return qu.q[++qu.front];
}

  void printQueue(void)
  {
   int i;
   for(i=qu.rear;i>=qu.front+1;i--)
    printf("%d",qu.q[i]);
   printf("\n"); 
    
  }