exception_test.cpp

#include <iostream>
#include <stdexcept>
#include <string>

class CompilerError : public std::runtime_error
{
    public:
    CompilerError(const std::string& what_arg)
        : std::runtime_error(what_arg)
    { }
};

class ScannerError : CompilerError
{
    public:
    ScannerError(const std::string& msg)
        : CompilerError(msg) { }
};

int main()
{
    try
    {
        throw ScannerError("An exception!");
    }
    catch(CompilerError& e)
    {
        std::cout << e.what() << '\n';
    }
    return 0;
}