[C++] global exception handling

#include <iostream>

using namespace std;

class CustomException : public exception {
private:
    string message;

public:
    CustomException(const char* msg): message(msg) {}

    const char* what() const throw()
    {
        return message.c_str();
    }
};

void run()
{
    throw CustomException("IllegalArgumentException");
}

/*
* global exception handling
*/
int main()
{
    try
    {
        run();
    }
    catch (CustomException& ex)
    {
        cout << ex.what() << endl;
    }
}