Stonwth.h

#ifndef STONEWT_h_
#define STONEWT_h_
#include <iostream>
using namespace std;
enum Mode{STONE,POUNDS};//方便main115,cpp
class Stonewth
{
private:
	
	enum {Lbs_per_stn=14};
	Mode mode;
	int stone;
	double pds_left;
	double pounds;
public:
	Stonewth(double lbs)
	{
		mode=POUNDS;//用于控制输出什么格式
		stone=int(lbs)/Lbs_per_stn;
		pds_left=int(lbs)%Lbs_per_stn+lbs-int(lbs);
		pounds=lbs;
	};
	Stonewth(){
		mode=POUNDS;//默认为镑
		stone=pds_left=pounds=0;
	};
	Stonewth(int stn,double lbs)
	{
		mode=POUNDS;
		stone=stn;
		pds_left=lbs;
		pounds=stn*Lbs_per_stn+lbs;
	};
	void setMode(Mode form=STONE)
	{
		if(form==STONE)
			mode=STONE;
		else if(form==POUNDS)
			mode=POUNDS;
		else
			cout<<"Invail mode !"<<endl;
	}
	Stonewth operator+(const Stonewth &s)const//这里我就选最简单的了
	{
		double newpounds=pounds+s.pounds;
		return Stonewth(newpounds);
	}
	Stonewth operator-(const Stonewth &s)const
	{
		double newpounds=pounds-s.pounds;
		return Stonewth(newpounds);
	}
	Stonewth operator*(double m)const//我这里选择重载常数*
	{
		double newpounds=pounds*m;
		return Stonewth(newpounds);
	}


	friend ostream& operator<<(ostream &os,const Stonewth &s)
	{
		if(s.mode==STONE)
			os<<s.stone<<"  stone!"<<endl;
		else if(s.mode==POUNDS)
			os<<s.pounds+s.pds_left<<"  pounds!"<<endl;
		else
			os<<"error!"<<endl;
		return os;
	}



};
#endif

main115.cpp

#include <iostream>
#include "stonewt.h"
using namespace std;
void main115()
{
	Stonewth s1;
	Stonewth s2(10,5);
	Stonewth s3(1.5);
	//cout<<s2<<endl;
	s2.setMode(STONE);
	s3.setMode(STONE);
	//cout<<s2<<endl;
	//cout<<s1<<endl;
	//cout<<s2<<endl;
	//cout<<s3<<endl;
	Stonewth s4=s2-s3;
	cout<<s4<<endl;
	cin.get();

}