C++：定义类时，使用构造函数

#pragma once
class Circle
{
public://无参数的构造函数Circle();//有参数的构造函数Circle(double x, double y, double radius);~Circle();
public://方法&＃xff0c;描述行为&＃xff0c;设置圆心位置void setCenter(double x, double y);//方法&＃xff0c;描述行为&＃xff0c;设置半径void setRadius(double radius);//方法&＃xff0c;描述行为&＃xff0c;获得圆的面积double getArea();private://数据成员&＃xff0c;描述对象的属性——圆心double m_x, m_y;//数据成员&＃xff0c;描述对象的属性——半径double m_radius;};

#include "stdafx.h"
#include "Circle.h"#include
using namespace std;
//无参数的构造函数,构造函数前面不能有数据类型
Circle::Circle()
{m_x &＃61; 0;m_y &＃61; 0;m_radius &＃61; 1;
}//有参数的构造函数
Circle::Circle(double x, double y, double radius)
{m_x &＃61; x;m_y &＃61; y;m_radius &＃61; radius;
}Circle::~Circle()
{
}
//方法&＃xff0c;描述行为&＃xff0c;设置圆心位置
void Circle::setCenter(double x, double y)
{m_x &＃61; x;m_y &＃61; y;
}
//方法&＃xff0c;描述行为&＃xff0c;设置半径
void Circle::setRadius(double radius)
{m_radius &＃61; radius;
}
//方法&＃xff0c;描述行为&＃xff0c;获得圆的面积
double Circle::getArea()
{return 3.14* m_radius *m_radius;
}

// myCircle20220503.cpp : 定义控制台应用程序的入口点。
//#include "stdafx.h"
#include "Circle.h"#include
using namespace std;int _tmain(int argc, _TCHAR* argv[])
{Circle myCircle1;myCircle1.setCenter(2, 5);myCircle1.setRadius(10);cout <<"圆的面积是&＃xff1a;" <}

UML类图&＃xff1a;

运行结果&＃xff1a;