[求助]谭浩强的《C++程序设计》的一个例题???
是2004年6月第1版,例子12.1。我怎么运行出错呀?编译器是VS2008。/*建立一个point类,包含数据成员x,y(坐标点)。以它为基类,派生出一个circle类...
是2004年6月第1版,例子12.1。我怎么运行出错呀?编译器是VS2008。
/*建立一个point类,包含数据成员x,y(坐标点)。以它为基类,派生出一个circle类,
增加数据成员r,再以circle类为直接基类,派生出一个cylinder类,再增加数据成员h。
要求编写程序,重载运算符“<<”和“<<”,使之能用于输出以上类对象*/
#include<iostream>
using namespace std;
//声明类
class point
{
public:
point(float x=0,float y=0);
void setpoint(float,float);
float getx() const { return x; }
float gety() const { return y; }
friend ostream & operator<<(ostream &,const point &);
protected:
float x,y;
};
//构造函数
point::point(float a,float b)
{ x=a; y=b; }
//设置坐标值
void point::setpoint(float a,float b)
{ x=a; y=b; }
//重载运算符,使之能输出点的坐标
ostream & operator<<(ostream &output,const point &p)
{
output<<"["<<p.x<<","<<p.y<<"]"<<endl;
return output;
}
//派生类
class circle:public point
{
public:
circle(float x=0,float y=0,float r=0);
void setradius(float);
float getradius() const;
float area() const;
friend ostream &operator<<(ostream &,const circle &);
float radius;
};
//定义构造函数,对圆心坐标和半径初始化
circle::circle(float a,float b,float r):point(a,b),radius(r) {}
void circle::setradius(float r)
{ radius=r; }
float circle::area() const
{ return 3.14159*radius*radius; }
ostream &operator<<(ostream &output,const circle &c)
{
output<<"Center=["<<c.x<<","<<c.y<<"],r="<<c.radius<<",area="<<c.area()<<endl;
return output;
}
//派生类cylinder
class cylinder:public circle
{
public:
cylinder(float x=0,float y=0,float r=0,float h=0);
void setheight(float);
float getheight() const;
float area() const;
float volume() const;
friend ostream &operator<<(ostream &,const cylinder&);
protected:
float height;
};
//定义
cylinder::cylinder(float a,float b,float r,float h):circle(a,b,r),height(h) {}
void cylinder::setheight(float h) { height=h; }
float cylinder::getheight() const { return height; }
float cylinder::area() const
{
return 2*circle::area()+2*3.14159*radius*height;
}
float cylinder::volume() const
{ return circle::area()*height; }
ostream &operator<<(ostream &output,const cylinder &cy)
{
output<<"Center=["<<cy.x<<","<<cy.y<<"],r="<<cy.radius<<",h="<<cy.height<<"\nare="<<cy.area()<<",volume="<<cy.volume()<<endl;
return output;
}
//main
int main(void)
{
cylinder cy1(3.5,6.4,5.2,10);
cout<<"\noriginal cylinder:\nx="<<cy1.getx()<<",y="<<cy1.gety()<<",r=";
cout<<cy1.getradius()<<",h="<<cy1.getheight()<<"\narea="<<cy1.area();
cout<<",volume="<<cy1.volume()<<endl;
cy1.setheight(15);
cy1.setradius(7.5);
cy1.setpoint(5,5);
cout<<"\nnew cylinder:\n"<<cy1;
point&pref=cy1;
cout<<"\npref as a point:"<<pref;
circle&cref=cy1;
cout<<"\ncref as a circle:"<<cref;
return 0;
}
1>code.obj : error LNK2019: 无法解析的外部符号 "public: float __thiscall circle::getradius(void)const " (?getradius@circle@@QBEMXZ),该符号在函数 _main 中被引用
1>D:\Program files\Samples\point\Debug\point.exe : fatal error LNK1120: 1 个无法解析的外部命令 展开
/*建立一个point类,包含数据成员x,y(坐标点)。以它为基类,派生出一个circle类,
增加数据成员r,再以circle类为直接基类,派生出一个cylinder类,再增加数据成员h。
要求编写程序,重载运算符“<<”和“<<”,使之能用于输出以上类对象*/
#include<iostream>
using namespace std;
//声明类
class point
{
public:
point(float x=0,float y=0);
void setpoint(float,float);
float getx() const { return x; }
float gety() const { return y; }
friend ostream & operator<<(ostream &,const point &);
protected:
float x,y;
};
//构造函数
point::point(float a,float b)
{ x=a; y=b; }
//设置坐标值
void point::setpoint(float a,float b)
{ x=a; y=b; }
//重载运算符,使之能输出点的坐标
ostream & operator<<(ostream &output,const point &p)
{
output<<"["<<p.x<<","<<p.y<<"]"<<endl;
return output;
}
//派生类
class circle:public point
{
public:
circle(float x=0,float y=0,float r=0);
void setradius(float);
float getradius() const;
float area() const;
friend ostream &operator<<(ostream &,const circle &);
float radius;
};
//定义构造函数,对圆心坐标和半径初始化
circle::circle(float a,float b,float r):point(a,b),radius(r) {}
void circle::setradius(float r)
{ radius=r; }
float circle::area() const
{ return 3.14159*radius*radius; }
ostream &operator<<(ostream &output,const circle &c)
{
output<<"Center=["<<c.x<<","<<c.y<<"],r="<<c.radius<<",area="<<c.area()<<endl;
return output;
}
//派生类cylinder
class cylinder:public circle
{
public:
cylinder(float x=0,float y=0,float r=0,float h=0);
void setheight(float);
float getheight() const;
float area() const;
float volume() const;
friend ostream &operator<<(ostream &,const cylinder&);
protected:
float height;
};
//定义
cylinder::cylinder(float a,float b,float r,float h):circle(a,b,r),height(h) {}
void cylinder::setheight(float h) { height=h; }
float cylinder::getheight() const { return height; }
float cylinder::area() const
{
return 2*circle::area()+2*3.14159*radius*height;
}
float cylinder::volume() const
{ return circle::area()*height; }
ostream &operator<<(ostream &output,const cylinder &cy)
{
output<<"Center=["<<cy.x<<","<<cy.y<<"],r="<<cy.radius<<",h="<<cy.height<<"\nare="<<cy.area()<<",volume="<<cy.volume()<<endl;
return output;
}
//main
int main(void)
{
cylinder cy1(3.5,6.4,5.2,10);
cout<<"\noriginal cylinder:\nx="<<cy1.getx()<<",y="<<cy1.gety()<<",r=";
cout<<cy1.getradius()<<",h="<<cy1.getheight()<<"\narea="<<cy1.area();
cout<<",volume="<<cy1.volume()<<endl;
cy1.setheight(15);
cy1.setradius(7.5);
cy1.setpoint(5,5);
cout<<"\nnew cylinder:\n"<<cy1;
point&pref=cy1;
cout<<"\npref as a point:"<<pref;
circle&cref=cy1;
cout<<"\ncref as a circle:"<<cref;
return 0;
}
1>code.obj : error LNK2019: 无法解析的外部符号 "public: float __thiscall circle::getradius(void)const " (?getradius@circle@@QBEMXZ),该符号在函数 _main 中被引用
1>D:\Program files\Samples\point\Debug\point.exe : fatal error LNK1120: 1 个无法解析的外部命令 展开
4个回答
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circle类里的float getradius() const没给实现。
不过我用的是vc2005,如直接在类里加实现:
float getradius() const
{
return radius;
}
不过我用的是vc2005,如直接在类里加实现:
float getradius() const
{
return radius;
}
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float circle::getradius() const
{
return radius;
}
float circle::getradius() const
{
return radius;
}
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天啊,难不成你每一个都有运行过吗?这都被你发现了,我也是看得那本书,不过我只是发现了一些小程序里的问题,还没有都运行一下试呢,你历害!加油哦!
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