Which C++ standard is the default when compiling with g++?

Question

I have a piece of code that looks like the following. Let\'s say it\'s in a file named example.cpp

#include 
#include 

        

Answer 1

I'm guessing a default version of the C++ compiler gets called, but I don't know which?

This is only guessable by reading the documentation of your particular compiler version.

If using a recent GCC, I recommend first to understand what version are you using by running

g++ -v

or

g++ --version

and then refer to the version of the particular release of GCC. For example for GCC 7, read GCC 7 changes etc

Alternatively, run

g++ -dumpspecs

and decipher the default so called spec file.

BTW, you could ensure (e.g. in some of your common header file) that C++ is at least C++17 by coding

 #if __cplusplus < 201412L
 #error expecting C++17 standard
 #endif

and I actually recommend doing it that way.

PS. Actually, think of C++98 & C++17 being two different languages (e.g. like Ocaml4 and C++11 are). Require your user to have a compiler supporting some defined language standard (e.g. C++11), not some particular version of GCC. Read also about package managers.