用两个栈模拟一个队列

栈是先进后出的原理，即FILO，队列是先进先出的原理，即FIFO

#include <iostream>
using namespace std;
#define MAXSIZE 256
typedef struct stack
{
      int top;
      int stack[MAXSIZE];
}Stack;
 
void initQueue(Stack *s)             //初始化队列
{
      s->top=0;
}
 
void enQueue(Stack *s,int elem)     //入队
{
       if(s->top<MAXSIZE)
       {
       s->top++;                   //队首元素从以1开始
       s->stack[s->top]=elem;
       }
        
}
void deQueue(Stack *s1,Stack *s2)    //模拟出队
{
         
    if(s1->top>0)
    {
       while(s1->top>0)
        {
            s2->stack[++s2->top]=s1->stack[s1->top--];
        } 
       cout<<"deQueue:"<<s2->stack[s2->top]<<endl;
       s2->top--;
       if(s2->top>0)
         {
            while(s2->top>0)
              {
                 s1->stack[++s1->top]=s2->stack[s2->top--];
              }
         }
     }
     else
      {
         cout<<"queue is empty!";
      }
}
int main()
{
      Stack s1,s2;
      int array[]={1,2,3,4,5,6,7,8,9};
      int i;
      cout<<"init the queue:"<<endl;
      //初始化队列
       initQueue(&s1);
       initQueue(&s2);
      cout<<"enQueue:"<<endl;
      //入队操作
      for(i=0;i<9;i++)
        {
             enQueue(&s1,array[i]);
        }
      cout<<"deQueue:"<<endl;
      //出队
       deQueue(&s1,&s2);
      cout<<"deQueue:"<<endl;
       deQueue(&s1,&s2);
      cout<<"deQueue:"<<endl;
       deQueue(&s1,&s2);
       return 0;
}