c++ - 请求从“点*”转换为非标量类型“点”

我读了几篇类似的文章，或者我不明白他们必须提供什么，或者他们似乎没有适用。我是新来的，我会尽力遵守规则。

我们将在本课程的最后两周学习c ++，并在40小时内最终学习c ::，所以我是一个初学者。我熟悉C。

这是相关任务的一部分：

Part 1 [20 points]
Reading material:
Copy constructor: https://www.geeksforgeeks.org/copy-constructor-in-cpp/
References (the & symbol): https://www.geeksforgeeks.org/references-in-c/
------------------------------------------------------------------------------------------------------
Write a class Point representing a point in 2d.
The class will have the following public methods:
// constructor - sets the coordinates to be x,y
Point( int x, int y)
// copy constructor - creates a new point with the same
coordinates
Point(Point &copy)
// getters
int getX()
int getY()
// setters
void setX()
void setY()
// prints to screen the coordinates in the format (x,y)
void print()

我的实现：

点

#include <iostream>

using namespace std;

class Point {
   private:
   int x, y;

public:
    // Parameterized Constructor
    Point(int x1, int y1);

    ~Point();

    Point (const Point &p2);

    int getX();

    int getY();


    void setX(int x2);


    void setY(int y2);

    void print();
};

点.cpp

#include "Point.hpp"

Point::Point(int x1, int y1)
    {
        x = x1;
        y = y1;
    }
Point::Point (const Point &p2)
    {
        x = p2.x;
        y = p2.y;
    }

int Point::getX()
    {
        return x;
    }

int Point::getY()
    {
        return y;
    }

void Point::setX(int x2)
    {
      x = x2;
    }

void Point::setY(int y2)
    {
      y = y2;
    }

void Point::print()
    {
        cout << "(" << x << "," << y << ")";
    }

我坚持的问题部分

Part 2 [20 points]
Reading material:
Abstract classes and pure virtual methods:
https://www.geeksforgeeks.org/pure-virtual-functions-and-abstract-classes/
---------------------------------------------------------------------------------------------------
Write an abstract class GeometricShape representing an abstract geometric
shape. The class will have the following public methods:
// Constructor: gets a coordinate. The purpose of the
coordinate depends on the specific shape
GeometricShape(Point coord)
// returns the area of the shape
// returns 0 as default. To be implemented in each
concrete shape
virtual float getArea() { return 0 ; }
// returns the perimeter of the shape
// returns 0 as default. To be implemented in each
concrete shape
virtual float getPerimeter() { return 0 ; }
// virtual method. To be implemented in each concrete
method
virtual void print() = 0 ;

我的实现：

GeometricShape.hpp

#include <iostream>
#include "Point.hpp"

using namespace std;

class GeometricShape {

private:
    Point point;

public:
    // Parameterized Constructor
    GeometricShape(Point coord);

    virtual float getArea();

    virtual float getPerimeter();

    virtual void print() = 0;
};

GeometricShape.cpp（这不会编译）

#include <iostream>
#include "GeometricShape.hpp"


GeometricShape::GeometricShape(Point coord)

{

Point p = new Point(coord.getX(),coord.getY());


}

int main()
{
  return 0;
}

在Linux Ubunto 18.04.3上编译时出现错误消息（可远程访问大学实验室，需要在实验室中的Linux上进行编译的分配）

错误信息：

gsg27@csil-cpu2:~/sfuhome/cmpt-125/5$ g++ GeometricShape.cpp
GeometricShape.cpp: In constructor ‘GeometricShape::GeometricShape(Point)’:
GeometricShape.cpp:9:11: error: conversion from ‘Point*’ to non-scalar type ‘Point’ requested
 Point p = new Point(coord.getX(),coord.getY());
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

最佳答案

您的直接问题是该行

Point p = new Point(coord.getX(),coord.getY());

没有道理。 new表达式返回指向动态分配对象的指针。因此，您编写的代码应该是

Point *p = new Point(coord.getX(),coord.getY());

除了您不需要指针，并且不需要动态分配的对象之外，您只是在尝试初始化数据成员。所以实际上您的构造函数应该是

GeometricShape::GeometricShape(Point coord) : point(coord) {}

因为您已经有数据成员GeometricShape::point，并且Point类具有副本构造函数。写起来会更平常

GeometricShape::GeometricShape(Point const &coord) : point(coord) {}

因为您不需要制作两个原始副本，但这在这里没什么大不了的。

关于c++ - 请求从“点*”转换为非标量类型“点”，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/59205063/