g++ 10.2 shows cpp version 14

Question

I am beginner in cpp.

I had a old cpp which version i dont know. I ran the following to check the version.

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";

    return 0;
}

Which outputs

c++14

After this, i tried to upgrade c++ version to latest c++ 20. Which i learned that each compilers support all different parts of c++. I downloaded mingw64 10.2 and added PATH variables.

If i run g++ --version, it correctly shows g++ version. However above code still prints that i am using c++14.

What am I missing?

Answer 1

You can set the C++ standard in gcc with the command line argument -std. Some of the supported standards are -std=c++11, -std=c++14, -std=c++17, -std=c++20.