#include "stdafx.h"
#include <iostream>
double hmean(double a, double b);
int main()
{
  double x, y, z;
  std::cout << "Enter two numbers: ";
  while (std::cin >> x >> y) {
    try
    {
      z = hmean(x, y);
    }
    catch(const char *s ){
      std::cout << s << std::endl;
      std::cout << " Enter a new pair of numbers: ";
      continue;
    }
    std::cout << "Harmonic mean of " << x << " and " << y << " is " << z << std::endl;
    std::cout << "Enter next set of numbers <q to quit>: ";
  }
  std::cout << "Bye! \n";
  system("pause");
  return 0;
}

double hmean(double a, double b) {
  if (a == -b) {
    throw "bad hmean() arguments a= -b not allowed";

  }
  return 2.0 *a*b / (a + b);
}

Enter two numbers: 3 6
Harmonic mean of 3 and 6 is 4
Enter next set of numbers <q to quit>: 10 -10
bad hmean() arguments a= -b not allowed
 Enter a new pair of numbers: q
Bye!
请按任意键继续. . .

   try
    {
      z = hmean(x, y);
    }

if (a == -b) {
    throw "bad hmean() arguments a= -b not allowed";

  }

catch(const char *s ){
      std::cout << s << std::endl;
      std::cout << " Enter a new pair of numbers: ";
      continue;
    }

#include "stdafx.h"
#include <iostream>

class bad_hmean
{
private:
  double v1;
  double v2;
public :
  bad_hmean(double a = 0, double b = 0) :v1(a), v2(b) {}
  void mesg();
};
inline void bad_hmean::mesg() 
{
  std::cout << "hmean ( " << v1 << " ," << v2 << ") ;"
    << "invalid argumnents: a =-b \n";
}

class bad_gmean
{
public :
  double v1;
  double v2;
  bad_gmean(double a = 0, double b = 0) :v1(a), v2(b) {}
  const char * mesg();
};
inline const char* bad_gmean::mesg() {
  return "gmean() arguments shoud be >=0 \n";
}

#include "stdafx.h"
#include <iostream>
#include <cmath>
#include "exc_mean.h"

double hmean(double a, double b);
double gmean(double a, double b);

int main()
{
  using std::cout;
  using std::cin;
  using std::endl;

  double x, y, z;
  1 >> 2;
  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 next set of numbers <q to quit >:";
    }
    catch (bad_hmean & bg)
    {
      bg.mesg();
      cout << "Try again. \n";
      continue;
    }
    catch (bad_gmean & hg)
    {
      cout << hg.mesg();
      cout << "Value used: " << hg.v1 << " ," << hg.v2 << endl;
      cout << "Sorry, you don't get to play any more .\n ";
      break;
    }

  }
  cout << " Bye! \n";
  system("pause");
  return 0;
  return 0;
}

double hmean(double a, double b) {
  if (a == -b)
    throw bad_hmean(a, b);
  return 2.0 * a*b / (a + b);
}
double gmean(double a, double b) {
  if (a < 0 || b < 0) throw bad_gmean(a, b);
  return std::sqrt(a * b);
}

输出结果:
Enter two numbers 4 12
Harmonic mean of 4 and 12 is 6
 Geometric mean of 4 and 12 is 6.9282
 Enter next set of numbers <q to quit >:5 -5
hmean ( 5 ,-5) ;invalid argumnents: a =-b
Try again.
5 -2
Harmonic mean of 5 and -2 is -6.66667
gmean() arguments shoud be >=0
Value used: 5 ,-2
Sorry, you don't get to play any more .
 Bye!
请按任意键继续. . .

double harm(double a ) throw(bad_thing);//可能会抛出 bad_thing异常
double marm(double ) throw() ;//不抛出异常

double marm() noexcept;

typedef void (*terminate_handle)() ;
terminate_handle set_terminate(terminate_handle f) throw();//c++ 98
terminate_handle set_terinate(terminate_handle f) noexcept; //c++11
void teminate(); //c++98
void teminate() noexcept ; //c++11

void myQuit()
{
  std::cout << "Terminating due to uncaught exception \n";

  system("pause");
}

在程序开始时执行:
set_terminate(myQuit);

typedef void (* unexpected_handle)();
unexpected_handle set_unexpected(unexpected_handle f) throw();//c++98
unexpected_handle set_unexpected(unexpected_handle f) noexpect;//c++11
void unexpected(); c++ 98
void unexpected() noexcept ;//c+ 0x

void myUnexpected() {
  throw std::bad_exception(); // or just throw ;
}
在程序开始时:
set_unexpected(myUnexpected);