C++队列的循环实现：

const int MAXQUEUE = 10;template
      
       class ZtkQueue {public:    ZtkQueue();    bool empty() const;    ErrorCode append(const T &x);    ErrorCode serve();    ErrorCode retrieve (T &x)const;    bool full() const;    int size() const;    void clear();    ErrorCode serve_and_retrieve(T &x);private:    int count;    int rear;    int front;    T entry[MAXQUEUE];};template
       
        ZtkQueue
        
         ::ZtkQueue():count(0),front(0),rear(MAXQUEUE-1){}template
         
          ErrorCode ZtkQueue
          
           ::serve_and_retrieve(T &x){    ErrorCode outcome = success;    if(count > 0)    {        count--;        x=entry[front];        front = ((front+1)==MAXQUEUE)?0:front+1;    }    else        outcome = underflow;    return outcome;}template
           
            void ZtkQueue
            
             ::clear(){ count=0; rear=MAXQUEUE - 1; front=0;}template
             
              int ZtkQueue
              
               ::size() const{ return count;}template
               
                bool ZtkQueue
                
                 ::full() const{ if(count == MAXQUEUE) return true; else return false;}template
                 
                  ErrorCode ZtkQueue
                  
                   ::retrieve(T &x) const{ ErrorCode outcome = success; if(!empty()) x = entry[front]; else outcome = underflow; return outcome;}template
                   
                    ErrorCode ZtkQueue
                    
                     ::serve(){ ErrorCode outcome = success; if(count>0) { count--; front = ((front+1)==MAXQUEUE)?0:front+1; } else outcome = underflow; return outcome;}template
                     
                      bool ZtkQueue
                      
                       ::empty()const{ if(count>0) return false; else return true;}template
                       
                        ErrorCode ZtkQueue
                        
                         ::append(const T &x){ ErrorCode outcome = success; if(count < MAXQUEUE) { count++; rear = ((rear+1)==MAXQUEUE)?0:rear+1; entry[rear]=x; } else outcome = overflow; return outcome;}