Question

我收到这些错误：

circleType.cpp||In function 'std::ostream& operator<<(std::ostream&, circleType&)':|
circleType.cpp|48|error: 'getRadius' was not declared in this scope|
circleType.cpp|49|error: 'circumference' was not declared in this scope|
circleType.cpp|50|error: 'area' was not declared in this scope|
||=== Build finished: 3 errors, 0 warnings (0 minutes, 0 seconds) ===|

错误可在此处找到：

ostream& operator <<(ostream& outs, circleType& circle1)
{
   outs << "radius: " << getRadius() << endl
   << "circumference: " << circumference() << endl
   << "area: " << area() << endl;
   return outs;
}

举个例子，这是圆周函数：

double circleType::circumference()
{
    return (radius*2*pi);
}

标题文件：

class circleType
{
public:
    circleType(); // færibreytulaus smiður
    circleType(double the_radius);
    double getRadius();
    void setRadius(double the_radius);
    double area();
    double circumference();
    friend ostream& operator <<(ostream& outs, circleType& );
private:
    double radius;
};

主：

circleType circle1(3.0);
cout << "circle1:" << endl;
cout << "--------" << endl;
cout << circle1 << endl;

所有标题都包含在任何地方。我仍然对过载功能有点困惑，任何帮助都很适合。

Answer 1

您没有在输入对象（circle1）上调用成员函数;相反，你试图用一些不存在的相同名称来调用一些全局函数（请注意friend函数不是该类的成员函数，它是它的朋友。，而是一个免费的非成员函数，可以访问该类的内部函数。）

要解决此问题，请更改重载operator <<的定义，如下所示：

ostream& operator << (ostream& outs, circleType& circle1)
{
   outs << "radius: " << circle1.getRadius() << endl
   << "circumference: " << circl1.circumference() << endl
   << "area: " << circle1.area() << endl;
   return outs;
}

超载 - 不在范围内

1 个答案: