How to throw std::exceptions with variable messages?

Question

This is an example of what I often do when I want to add some information to an exception:

std::stringstream errMsg;
errMsg << \"Could not load config          


        

Answer 1

Use string literal operator if C++14 (operator ""s)

using namespace std::string_literals;

throw std::exception("Could not load config file '"s + configfile + "'"s);

or define your own if in C++11. For instance

std::string operator ""_s(const char * str, std::size_t len) {
    return std::string(str, str + len);
}

Your throw statement will then look like this

throw std::exception("Could not load config file '"_s + configfile + "'"_s);

which looks nice and clean.