作业

4-20
/*#include
using namespace std;

class Complex
{
public:
Complex(double a,double b);
void add(Complex b);
void show();
private:
double c,d;
};
Complex :: Complex(double a=0,double b=0)///不同于下面的那个方法，此方法运用了默认形参值
{
c=a;d=b;
}
void Complex :: add(Complex b)
{
c=c+b.c;
d=d+b.d;
}
void Complex :: show()
{
cout<<"c="<<c<<"+"<<d<<"i"<<endl;
}
int main()
{
Complex c1(3,5);
Complex c2(4.5);
c1.add(c2);
c1.show();
return 0;
}*/

include

using namespace std;

class Complex
{
public:
Complex(double a,double b);
Complex(double a);
void add(Complex b);
void show();
private:
double c,d;
};

Complex :: Complex(double a,double b)
{
c=a;d=b;
}
Complex :: Complex(double a)
{
c=a;d=0;
}
void Complex :: add(Complex b)
{
c=c+b.c;
d=d+b.d;///等式右边的c和d是类里面的私有元素，可以使用的。
}
void Complex :: show()
{
cout<<"c="<<c<<"+"<<d<<"i"<<endl;
}

int main()
{
Complex c1(3,5);
Complex c2(4.5);
c1.add(c2);
c1.show();
return 0;
}

4-11

include

using namespace std;

class Rectangle
{
public:
Rectangle(double a,double b);///构造函数进行初始化
double s();///用来求面积的函数
private:
double A,B;
};

Rectangle :: Rectangle(double a,double b)
{
A=a;B=b;
}
double Rectangle :: s()
{
return A*B;
}

int main()
{
Rectangle r(5,4);
cout<<r.s();
return 0;
}