模板标识符 不匹配任何模板声明

第一种办法是在前面加 

template <class T>

class SeqQueue;

template <class T>

std::ostream& operator <<(std::ostream& os, SeqQueue<T>& Q);

//顺序队列的定义

template <class T>

class SeqQueue{

public:

        SeqQueue(int sz = 10);

        ~SeqQueue(){delete []elements;}

        bool isFull(){return ((rear + 1) % maxSize == front)? true: false;} //判断队列是否满

        bool isEmpty(){return (front == rear)? true: false;} //判断队列是否空

        bool EnQueue(const T& x); //入列

        bool DeQueue(); //出列

        friend ostream& operator<<<T>(ostream& os, SeqQueue<T>& Q); //重载栈中元素的输出操作

protected:

        int rear, front; //队尾；队头指针

        int maxSize, tag; //队列最大可容纳的元素个数；标记

        T* elements; //存放队列元素的数组

};

template <class T>

ostream& operator<<(ostream& os, SeqQueue<T>& Q){

        int num;

        if(Q.front==Q.rear && Q.tag==1)

            num=Q.maxSize;

        else

                num=(Q.rear - Q.front + Q.maxSize) % Q.maxSize;

        for(int i = Q.front; i != Q.rear; i = (i + 1) % Q.maxSize)

                os<<i<<":"<<Q.elements[i]<<endl;

        return os;

}

第二种方法,就是直接在模板中实现在,即: 
template  
class Array{ 
public: 
........something...... 
friend ostream& operator<< (ostream& out,Array&rhs){ 
.......something..... 
} 
};