How to get c++ default version after install ROS ?

edit

For Ubuntu, you can check in command terminal.

`gcc --version`

or

`aptitude show gcc`

If you want to check in code:

#include <iostream>
#include <typeinfo>

int main()
{
    if (__cplusplus == 201703L) std::cout << "C++17\n";
    else if (__cplusplus == 201402L) std::cout << "C++14\n";
    else if (__cplusplus == 201103L) std::cout << "C++11\n";
    else if (__cplusplus == 199711L) std::cout << "C++98\n";
    else std::cout << "pre-standard C++\n";

}