Question

我正在构建一个类实现，我想使用在用作参数的类中定义的结构。以下是一些有用的代码：

void Polynomial::naivePrint()
{
    //start reading the terms from the beginning
    Term* pos = first;
    //print all of the terms in the polynomial
    while(pos != NULL){
        std::cout << "y=" << pos->coeff << "x^" << pos->power;
        //print a plus until we get to the last term
        if(pos->next != NULL){
            std::cout << "+";
        }
        pos = pos->next;
        }
    std::cout<<endl;
}

我想把它放到一个ostream朋友函数中，所以我尝试了这个：

std::ostream & operator << (std::ostream &out, const Polynomial &Poly)
{
   //start reading the terms from the first term
   Term* pos = Poly.first;
   //print all of the terms in the polynomial
   while(pos != NULL){
       out << "y=" << pos->coeff << "x^" << pos->power;
      //print a plus until we get to the last term
      if(pos->next != NULL){
         out << "+";
      }
      pos = pos->next;
   }
   out<<endl;
}

告诉我‘Term’ was not declared in this scope。

所以我尝试了Poly.Term* pos = Poly.first;

其中说invalid use of ‘struct Polynomial::Term’

我是否可以使用参数类中声明的结构类型来声明变量？

Answer 1

Term在Polynomial内定义，因此在Polynomial::Term类的范围之外使用时，需要使用全名Polinomial来引用它。< / p>

Polynomial::Term* pos = Poly.first;

我有一个在类中定义的结构。如何在朋友功能中使用它？

1 个答案: