错误C2039:"getNumberOfCorners":不是"Shape"的成员 [英] error C2039: 'getNumberOfCorners' : is not a member of 'Shape

问题描述

我遇到的错误是错误C2039:" getNumberOfCorners":不是C ++中"Shape"的成员如何解决?

解决方案

<一旦将其向下转换为形状，Circle类中的方法将不可见.您已经将它们扔掉了(或至少将它们隐藏了).当您具有形状类时，仅Shape上的方法可见.派生类型是什么无关紧要，您需要将其强制转换为该类型.

Gosh.好吧，C ++中没有Shape类，所以我想问题可能出在您正在使用的某个类上，该类不包含名为getNumberOfCorners的方法，称为Shape.

你想做什么 ?这个班是从哪里来的?为什么无法理解基本错误消息?是什么让您认为此方法应该存在?

好吧，我尝试编写形状层次结构.一个抽象基类(其名称为Shape)，该类包含两个纯虚函数(totalArea& shapeName)，然后从Shape类继承twoDshape抽象类. twoDshape类也包含两个抽象函数. (perimeter& numberOfCorners)，然后我从twoDshape实现一个具体的类.它的名字叫圆....

最后，我的问题是； :)

然后我制作一个形状指针，然后我使用->操作员达到对象的周边功能...

圈出myCircle; //我的圈子对象

形状* sPtr =& myCircle;

cout<< sPtr-> perimeter(); //我在这行有问题

它说:perimeter()不是形状的成员

I have an error which is "error C2039: ''getNumberOfCorners'' : is not a member of ''Shape" in C++ how can we correct ?

解决方案

Once you downcast it to a shape, the methods in the Circle class are not visible. You''ve thrown them away ( or at least, hidden them ). Only methods on Shape are visible, when you have a shape class. It is irrelevant what the derived type is, you need to cast it to that type.

Gosh. Well, there''s no Shape class in C++, so I guess the problem must lie with some class you''re using, a class which does NOT contain a method called getNumberOfCorners, and is called Shape.

What are you trying to do ? Where did this class come from ? Why can''t you understand a basic error message ? What makes you think that this method should exist ?

well i try to write a shape hierarchy. an abstract base class (its name is Shape) and that class contain two pure virtual functions (totalArea & shapeName ) and then i inherit twoDshape abstract class from Shape class. twoDshape class contains two abstract functions, too. (perimeter & numberOfCorners) then i implement a concrete class from twoDshape. And its name is circle....

Finally, my problem is ; :)

Then i make a shape pointer and i use -> operator to reach to perimeter function of the object...

circle myCircle; //my circle object

shape *sPtr = &myCircle;

cout << sPtr->perimeter() ; // i have the problem in this line

it says: perimeter() is not member of shape

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