Обработка исключений

#include <iostream>
#include <stdexcept>
#include <limits>
 
using namespace std;
 
double div(double a, double b) throw(underflow_error)
{
    double result = a / b;
    if ( result < numeric_limits<double>::min() )
        throw underflow_error("underflow!");
    return result;
}
 
int main()
{
    try {
        div(numeric_limits<double>::min(), numeric_limits<double>::max());
    } catch (const exception &e) {
        cout << e.what();
    }
    return 0;
}

    double result = a / b;
    if ( a && result < numeric_limits<double>::min() )

if ( a && (a / b) < numeric_limits<double>::min() )

#include <iostream>
#include <limits>
 
int main()
{
    double max = std::numeric_limits<double>::max();
    double min = std::numeric_limits<double>::min();
    if ( min / max < min ) std::cout << "undeflow??";
    return 0;
}

#include <iostream>
#include <limits>
 
int main()
{
    double max = std::numeric_limits<double>::max();
        double min = std::numeric_limits<double>::min();
        //if ( 5 < min ) std::cout << "undeflow??";
    std::cout << min/max;
    return 0;
}

#include <iostream>
 
int main()
{
    double a, b, c;
    std:: cin >> a >> b;
 
    if (!b)
        std::cout << "On zero divide!";
    else
    {
       c = a/b; 
       if (a == 0 || c) 
        std::cout << "Everything is going to be ok";
       else
        std::cout << "Underflow!";
    } 
}

double _div(double a, double b) throw(underflow_error)
{
    double result = a / b;
    if (a && result == 0.0)
        throw underflow_error("underflow!");
    return result;
}