C++PrimerPlus第十一章类的使用，类自动类型转换和强制类型转换（重量单位：英石和磅的转换）0003

程序清单 11.21对新的转换函数进行测试。该程序中的赋值语句使用隐式转换，而最后的cout 语句使用显式强制类型转换。请务必将程序清单 11.20与程序清单11.21一起编译。

//stonewt.cpp -- Stonewt methods
#include<iostream>
#include"stonewt1.h"
using std::cout;

//construct Stonewt object from double value
Stonewt::Stonewt(double lbs)
{
	stone = int(lbs) / Lbs_per_stn;//integer division
	pds_left = int(lbs) % Lbs_per_stn + lbs - int(lbs);
	pounds = lbs;
}


//construct Stonewt object from stone,double values
Stonewt::Stonewt(int stn, double lbs)
{
	stone = stn;
	pds_left = lbs;
	pounds = stn * Lbs_per_stn + lbs;
}


//default construct Stonewt wt = 0
Stonewt::Stonewt()
{
	stone = pounds = pds_left = 0;
}

//destructor
Stonewt::~Stonewt()
{

}

//show weight in stones
void Stonewt::show_stn()const
{
	cout << stone << " stone, " << pds_left << " pounds\n";
}

//show weight in pounds
void Stonewt::show_lbs()const
{
	cout << pounds << " pounds\n";
}

//conversion functions 
Stonewt::operator int()const
{
	return int(pounds + 0.5);
}

Stonewt::operator double()const
{
	return pounds;
}

下面引出测试函数，下一个文件中测试，这样分开方便阅读，有的小伙伴看到内容太多，都吓到了。