有关C++ 错误处理的两个有关问题

有关C++ 异常处理的两个问题
//set_new_handler处理new故障
#include <iostream>
#include <new>
#include <cstdlib>

using namespace std;

void customNewHandler()
{
  cerr<<"customNewHandler was called";
  abort();
}

int main()
{
  double *ptr[50];
  set_new_handler(customNewHandler);//依然调用了terminate函数而不是正常退出，为什么呢？

  for(int i = 0;i<50;i++)
  {
  ptr[i] = new double[50000000];
  cout<<"Allocated 50000000 doubles in ptr["<<i<<"]\n";
  }

  return 0;
}

//栈展开
#include <iostream>
#include <stdexcept>
using namespace std;

void function3()throw(runtime_error)// 函数定义后面为什么要加上throw(runtime_error)???
{
  cout<<"In function 3"<<endl;

  throw runtime_error("runtime_error in function3");
}

void function2()throw(runtime_error)//同上
{
  cout<<"function3 is called inside function2"<<endl;
  function3();
}

void function1()throw(runtime_error)
{
  cout<<"function2 is called inside function1"<<endl;
  function2();
}

int main()
{
  try
  {
  cout<<"function1 is called inside main"<<endl;
  function1();
  }
  catch(runtime_error &error)
  {
  cout<<"Exception occurred:"<<error.what()<<endl;
  cout<<"Exception handled in main"<<endl;
  }

  return 0;
}


[解决办法]

C/C++ code

void function3()throw(runtime_error)// 函数定义后面为什么要加上throw(runtime_error)???//不加在这里也没事，加了表示只能抛出runtime_error异常{  cout<<"In function 3"<<endl;  throw runtime_error("runtime_error in function3");}