12-4 捕获委托构造函数的异常

#include <iostream>

class X
{
public:
    X()
    try : X(0)
    {
    }
    catch (int e)
    {
        std::cout << "catch" << e << std::endl;
        throw 3;
    }

    X(int a)
    try : X(a, 0.)
    {
    }
    catch (int e)
    {
        std::cout << "catch" << e << std::endl;
        throw 2;
    }

    X(double b)
    try : X(0, b)
    {
    }
    catch (int e)
    {
        std::cout << "catch" << e << std::endl;
        throw 1;
    }

    X(int a, double b) : a_(a), b_(b) { throw 0; }

private:
    int a_;
    double b_;
};

int main()
{
    try
    {
        X x;
    }
    catch (int e)
    {
        std::cout << "catch" << e << std::endl;
    }
}