编写一个圆类Circle,该类拥有:

#include"stdio.h"constdoubleP=3.14;classCircle{public:virtualdoubleArea();voidR(doubles);doublegetr(

publicclassRectangle{privatedoublewidth;privatedoublelength;publicdoublegetWidth(){returnwidth;}publ

可以在父类中写虚函数的定义如果子类中重写了该虚函数,则根据指针可以调用到子类的虚函数；否则的话,调用的是父类的虚函数.极端情况下,纯虚函数也可以拥有定义,但由于不能生成父类的实例,定义出的函数不能直接

classcircle{intx;inty;floatradius;public:voidsetpoint(int&x,;int&y);voidsetradius(float&radius);floa

#includeusingnamespacestd;classComplex{public:Complex(){real=0;imag=0;}Complex(doubler,doublei){real

classcircle{public:circle(doubleradius):_radius(radius){}~circle(void);private:double_radius;public:

教材上一般都有,这是标准例题.

publicclassTest1{\x09publicstaticvoidmain(String[]args){\x09\x09for(charlowerCase='a',upperCase='A';

public class Test {\x09public static double area(double length,do

classcircle{floatradius;floatarea;public:circle(floatr){radius=r;}floatgetarea(void){area=3.14*radiu

把这三个类分别放到三个.java文件中,然后编译运行即可.publicclassCircle{privatedoubler;publicCircle(doubler){this.r=r;}public

#includeusingnamespacestd;classfraction{public:fraction(intn=1,intd=1){num=n;den=d;}fraction&operato

#include"iostream"#include"cmath"usingnamespacestd;classCircle{public: Circle(doublex=0,doubley

#includeusingnamespacestd;classPoint{public:\x09Point(floatx1=0,floaty1=0)/*Point的构造函数,默认圆点为(0,0)*/\

publicclassCircle{privatedoubleradius;publicCircle(doubler){this.radius=r;}publicstaticvoidmain(Stri

classa{publcstatevoidb(){}}

classCircle{privatedoubleradius;publicCircle(){this.radius=0;}publicCircle(doubler){this.radius=r;}p

#includeclasscircle{private:intr;public:voidinput(){cout

Console.WriteLine("请输入圆的半径");intr=int.Parse(Console.ReadLine());doublecircle=2*3.14*r;doublearea=3.1

根据题意实现代码如下：#include <iostream>#include <cmath>#include <string>usin