stonewt.cpp

我学习C++ Primer Plus过程中写下的课后作业的编程代码

// stonewt.cpp -- Stonewt methods
#include <iostream>
using std::cout;
#include "stonewt.h"

// constructor Stonewt object from double value
Stonewt::Stonewt( double lbs , char m)
{	
	if( 'p' == m || 's' == m )
	   mode = m;
	else
	{
		std::cerr<<"模式错误,设为默认值'p'.\n";
		mode = 'p';
	}
	mode = m;
	stone = int(lbs) / Lbs_per_stn;		// integer division
	pds_left = int(lbs) % Lbs_per_stn + lbs - int(lbs);
	pounds = lbs;
}

// constructor Stonewt object from stone, double values
Stonewt::Stonewt( int stn, double lbs, char m  )
{
	if( 'p' == m || 's' == m )
	   mode = m;
	else
	{
		std::cerr<<"模式错误,设为默认值'p'.\n";
		mode = 'p';
	}
	if( int(lbs) > Lbs_per_stn )		// 当lbs超过14 stone时
	{
		stone = stn + int(lbs) / Lbs_per_stn;
		pds_left = int(lbs) % Lbs_per_stn + lbs - int(lbs);
	}
	else
	{
	  stone = stn;
	  pds_left = lbs;
	}
	pounds = stn * Lbs_per_stn + lbs;
}

Stonewt::Stonewt()
{
	mode = 'p';
	stone = pounds = pds_left = 0;
}

Stonewt::~Stonewt()
{
}

void Stonewt::pds_mode ()
{
	mode = 'p';
}

void Stonewt::stn_mode ()
{
	mode = 's';
}

Stonewt Stonewt::operator+ ( const Stonewt & s )const
{
	return Stonewt ( pounds + s.pounds );
}

Stonewt Stonewt::operator- ( const Stonewt & s )const
{
	return Stonewt ( pounds - s.pounds );
}

Stonewt Stonewt::operator* ( const Stonewt & s )const
{
	return Stonewt ( pounds * s.pounds );
}

// show weight in stones
std::ostream & operator<< ( std::ostream & os, const Stonewt & s )
{
	if( 'p' == s.mode )
	{
		os<<s.pounds<<" pounds\n";
		return os;
	}
	else
	{
		os<< s.stone<<" stone, "<<s.pds_left <<" pounds\n";
		return os;
	}
}