exch.cpp

#include <stdexcept>
#include <iostream>
using namespace std;

class bad_hmean:public exception//logic_error我懒得去找logic_error的构造函数格式了，直接继承exception
{
public:
	//explicit bad_hmean(const string &what_arg){};
	const char *what(){
		return "bad argument to heanm(),不应该是相反数";
	}
};
class bad_gmean:public exception//logic_error
{
public:
	const char *what()
	{
		return "gmean() arguments should be >=0";
	}
};

main152.cpp

#include <iostream>
#include "exch.cpp"
using namespace std;

double hmean(double x,double y)
{
	//if(x=-y)别写成了我这样哈
	if(x==-y)
		throw bad_hmean();
	else
		return 2.0*x*y/(x+y);
};
double gmean(double x,double y)
{
	if(x<0||y<0)
		throw bad_gmean();
	else
		return sqrt(x*y);
};
void main152()
{
	double x,y,z;
	cout<<"Enter two numbers:";
	while(cin>>x>>y)
	{
		try{
			z=hmean(x,y);
			cout<<"Harmonic mean of "<<x<<"  and  "<<y
				<<"  is  "<<z<<endl;
			cout<<"Geometric mean of "<<x<<"  and  "<<y
				<<" is "<<gmean(x,y)<<endl;
			cout<<"Enter the next set of numbers <q to quit>:";
		}
		catch(bad_hmean &h)
		{
			//h.what();
			cout<<h.what()<<endl;
		}
		catch(bad_gmean &g)
		{
			cout<<g.what()<<endl;
		}
		cin.get();

	}

	cout<<"Bye"<<endl;
		cin.get();

}