//QuizShape.h
#ifndef QUIZSHAPE_H
#define QUIZHAPE_H
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
class QuizShape
{
protected:
//outer and inner symbols, and label
char border, inner;
string quizLabel;
public:
//base class constructor with defaults
QuizShape(char out = '*', char in = '+', string name = "3x3 Square")
{
border = out;
inner = in;
quizLabel = name;
cout << "base class constructor, values set" << endl << endl;
};
//getters
char getBorder() const
{ return border; }
char getInner() const
{ return inner; }
string getQuizLabel() const
{ return quizLabel; }
//virtual functions to be defined later
virtual void draw( ) = 0;
virtual int getArea( ) = 0;
virtual int getPerimeter( ) = 0;
};
class Rectangle : public QuizShape
{
protected:
//height and with of a rectangle to be drawn
int height, width;
public:
//derived class constructor
Rectangle(char out, char in, string name,
int h = 3, int w = 3):QuizShape(out, in, name)
{
height = h;
width = w;
cout << "derived class constructor, values set" << endl << endl;
}
//getters
int getHeight() const
{ return height; }
int getWidth() const
{ return width; }
//*********************************************
virtual void draw(const Rectangle &rect1)
{
cout << "draw func" << endl;
cout << rect1.height << endl;
cout << rect1.getWidth() << endl;
cout << rect1.getQuizLabel() << endl;
}
virtual int getArea(const Rectangle &rect2)
{
cout << "area func" << endl;
cout << rect2.getInner() << endl;
cout << rect2.getBorder() << endl;
}
virtual int getPerimeter(const Rectangle &rect3)
{
cout << "perim func" << endl;
cout << rect3.height << endl;
cout << rect3.getWidth() << endl;
cout << rect3.getQuizLabel() << endl;
}
//************************************************
};
#endif
这些是目前为止的类类型。
//QuizShape.cpp
#include "QuizShape.h"
这目前除了桥接文件外什么都不做。
//pass7.cpp
#include "QuizShape.cpp"
int main()
{
Rectangle r1('+', '-', "lol", 4, 5);
cout << r1.getHeight() << endl;
cout << r1.getWidth() << endl;
cout << r1.getInner() << endl;
cout << r1.getBorder() << endl;
cout << r1.getQuizLabel() << endl;
system("pause");
return 0;
}
由于 Rectangle 应该是一个抽象类,因此代码无法编译,当鼠标悬停在 main
中的 r1
声明上时,我收到错误消息
"Object of abstract class type "Rectangle" is not allowed".
我检查了本网站和其他网站上的其他答案,但没有找到解决问题的方法。
注意:我理解虚函数的语句以 =0 结尾;使类成为抽象类。 QuizShape 应该是抽象的。我已经在 Rectangle 中定义了虚函数,但它仍然是一个抽象类。
如何修改 Rectangle 类的虚函数,使 Rectangle 不再抽象?
最佳答案
抽象类 QuizShape
中的方法是:
virtual void draw( ) = 0;
virtual int getArea( ) = 0;
virtual int getPerimeter( ) = 0;
但在 Rectangle
中,它们将 const Rectangle &rect1
作为参数,因此您可以隐藏方法而不是覆盖抽象方法。 Rectangle
中的方法需要与抽象基类中的方法具有相同的签名。
关于c++ - 不允许抽象类类型 "Rectangle"的对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16073156/