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"
#include <cctype>

// 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 );
}

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

bool Stonewt::operator <= ( const Stonewt & s )const
{
	return pounds <= s.pounds;
}

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

bool Stonewt::operator >= ( const Stonewt & s )const
{
	return pounds >= s.pounds;
}

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

bool Stonewt::operator != ( const Stonewt & s )const
{
	return pounds != s.pounds;
}

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

/*
std::istream & operator>> ( std::istream & os, Stonewt & s )
{
	using std::cout;
	cout<<"请选择输入方式( p: pounds, s: stone and pds_left )\n";
	double Pounds = 0.0;
	int	   Stone = 0;
	double Pds_left = 0.0;
	char choose = 0;		// 在C++程序设计语言里看到有这种用法
	while(!os>>choose&&('p'!=(choose=tolower(choose))||'s'!=(choose= tolower(choose))))
	{
		os.clear();
		while( os.get(choose) != '\n' )
			continue;
		cout<<"输入不正确,请重新输入(p or s).\n";
		os>>choose;
	}
	while( os.get(choose) != '\n' )
		continue;
	if( 'p' == choose )
	{
		cout<<"请输入pounds(double): ";
		while( !os>>Pounds )
		{
			os.clear();
			while( os.get(choose) != '\n' )
				continue;
			cout<<"输入不正确,请重新输入(double).\n";
			os>>pounds;
		}
		while( os.get(choose) != '\n' )
			continue;
	}
	else
	{
		cout<<"请输入stone(int): ";
		while ( !os>>Stone )
		{
			os.clear();
			while( os.get(choose) != '\n' )
				continue;
			cout<<"输入不正确,请重新输入(int).\n";
			os>>Stone;
		}
		while( os.get(choose) != '\n' )
			continue;
		cout<<"请输入Pds_left(double): ";
		while ( !os>>Pds_left )
		{
			os.clear();
			while( os.get(choose) != '\n' )
				continue;
			cout<<"输入不正确,请重新输入(double).\n";
			os>>Pds_left;
		}
		while( os.get(choose) != '\n' )
			continue;
	}
	return os;
}
*/