第三章作业

3.22

#include<iostream>
#include<math.h>
using namespace std;
class Circle{
public:
void area(int x,double y);
void show();
private:
int radius;
double Area;
};
void Circle::area(int x,double y)
{
radius=x;
Area=y;
}
void Circle::show()
{
cout<<"半径为R的圆的面积为："<<Area<<endl;
}
int main()
{
Circle circle1;
int a;
double b;
cout<<"请输入圆的半径R：";
cin>>a;
b=3.14*a*a;
circle1.area(a,b);
circle1.show();
return 0;
}

3.23

#include<iostream>
using namespace std;
struct cylinder{
public:
void set(double x,double y,double z)
{
r=x;
h=y;
v=z;
};
void show();
private:
double r;
double h;
double v;
};
void cylinder::show()
{cout<<"该圆柱体的底面半径为："<<r<<endl<<"高为："<<h<<endl<<"体积是："<<v<<endl;}
int main()
{
cylinder vo1;
double a,b,c;
a=3.0;
b=4.0;
c=3.14*a*a*b;
vo1.set(a,b,c);
vo1.show();
return 0;
}

3.24

<p><pre name="code" class="cpp">#include<iostream>
using namespace std;
class Date{
public:
Date(int a,int b,int c);
Date();
void printDate();
void GetYear();
void GetMonth();
void GetDay();
void SetDate(int Y,int m,int d)
{
year=Y;
month=m;
day=d;
}
private:
int year;
int month;
int day;
};
Date::Date(int a,int b,int c):year(a),month(b),day(c)
{}
Date::Date()
{}
void Date::printDate()
{
cout<<year<<"."<<month<<"."<<day<<endl;
}
void Date::GetYear()
{
cout<<"输入一个年份：";
cin>>year;
}
void Date::GetMonth()
{
cout<<"输入一个月份：";
cin>>month;
}
void Date::GetDay()
{
cout<<"输入一个日子：";
cin>>day;
}
int main()
{
Date d1(2010,6,8);
d1.printDate();
Date d2;
d2.GetYear();
d2.GetMonth();
d2.GetDay();
d2.printDate();
Date d3(d1);
d3.printDate();
return 0;
}