Create inline std::string

Question

Is it possible to initialize a std::string without creating a variable?

What I wish to accomplish:

throw std::runtime_error("Error: " + strerror(errno));

What I do currently:

std::string error = "Error: ";
std::string errmsg(strerror(errno));
throw std::runtime_error(error + errmsg);

Answer 1

Just make a temporary out of one of them:

throw std::runtime_error(std::string("Error: ") + strerror(errno));

The operator+ overload for std::string can take const char* as well as std::string.

If you have access to C++14, you can using namespace std::literals and do it this way:

throw std::runtime_error("Error: "s + strerror(errno));