第三章作业

<span style="color: rgb(51, 51, 51); font-family: Arial; font-size: 14px; line-height: 26px;">第三章</span>

<span style="color: rgb(51, 51, 51); font-family: Arial; font-size: 14px; line-height: 26px;">【3.22】声明一个circle类，有数据成员radius（半径）、成员函数area（），计算圆的面积构造一个circle的对象进行测试。</span>

#include <iostream>using namespace std;class Circle{//声明圆类double r;//定义数据成员半径double s;//定义数据成员面积public:void rinput()//定义成员函数输入半径{cout<<"请输入半径:"<<endl;cin>>r;}void area()//定义成员函数输出面积{s=3.14*r*r;cout<<"半径为"<<r<<"的圆的面积为"<<s<<endl;}};int main(){Circle c1;//定义圆类对象c1.rinput();c1.area();return 0;}

<span style="color: rgb(51, 51, 51); font-family: Arial; font-size: 14px; line-height: 26px;">【3.23】建立类cylinder，cylinder的构造函数被传递了两个double值，分别表示圆柱体的半径和高度。用类cylinder计算圆柱体的体积，并存储在一个double变量中。在类cylinder中包含一个成员函数vol，用来显示每个cylinder对象的体积。</span>

<span style="color: rgb(51, 51, 51); font-family: Arial; font-size: 14px; line-height: 26px;"></span><pre name="code" class="cpp">#include <iostream>using namespace std;class cylinder{public:cylinder(double m,double n);//声明构造函数原型void vol();//显示对象函数private:double r;double h;double V;};cylinder::cylinder(double m,double n)//定义构造函数{cout<<"Constructing..."<<endl;r=m;h=n;   }void cylinder::vol(){V=r*h;cout<<"圆柱体的面积为："<<V<<endl;}int main(){cylinder A(5,6);A.vol();return 0;}

【3.24】定义一个日期类Date

<pre name="code" class="cpp">#include <iostream>using namespace std;class Date{public:void printDate();//显示日期void GetYear();//取年的值void GetMonth();//取月的值void GetDay();//取日的值void SetDate(int Y,int m,int d);//设置日期值Date(int a,int b,int c);//声明构造函数private:int Year;int Month;int Day;};void Date::printDate(){cout<<Year<<"年"<<Month<<"月"<<Day<<"日"<<endl;}void Date::GetYear(){cout<<"年份："<<Year<<endl;}void Date::GetMonth(){cout<<"月份："<<Month<<endl;}void Date::GetDay(){cout<<"日期："<<Day<<endl;}void Date::SetDate(int Y,int m,int d){cout<<"请依次输入年份 月份 日期"<<endl;cin>>Y>>m>>d;Year=Y;Month=m;Day=d;cout<<"输入的日期为："<<Year<<"年"<<Month<<"月"<<Day<<"日"<<endl;}Date::Date(int a,int b,int c)//定义构造函数{cout<<"Constructing..."<<endl;Year=a;Month=b;Day=c;}int main(){Date d1(2010,6,8);d1.printDate();Date d2(0,0,0);d2.SetDate(2015,4,1);Date d3(d1);d3.GetYear();d3.GetMonth();d3.GetDay();d3.printDate();return 0;}