CODEWITHSUNDEEP
c++c++11g++preprocessor-directive
Zombie Chibi XD
Zombie Chibi XD

Reputation: 386

Is it possible to set g++ to follow C++11 ISO (-std=c++11) through #define?

I'm quite new to c++11 and I was wondering something...

I am using Code::Blocks and if I were to use c++11 in this IDE, i had to go to compiler settings, and and Check "Have g++ follow the C++11 ISO C++ language standard"

Is there any workaround so I can set a single .cpp file to use c++11 in the #define statement like this?

Note: This is a single "Build" file, NOT a project

By setting the compile option while not in project, it'll set it to Global Compile option that I prefer to not happen

I know that you can customize the build option in Project Files that It'll set c++11 for that project only

#include <iostream>

#define -std c++11

int main(){

    #if __cplusplus==201402L
        std::cout << "C++14" << std::endl;
    #elif __cplusplus==201103L
        std::cout << "C++11" << std::endl;
    #else
        std::cout << "C++" << std::endl;
    #endif
    return 0;
}

What I have found:

Changing #define __cplusplus 201103L is NOT a good idea, because it don't set the compiler to compile as c++11

Upvotes: 8

Views: 864

Answers (3)

Toby Speight
Toby Speight

Reputation: 30871

Although I can see how it would be desirable for a source file to be self-documenting in this respect, this isn't possible.

The next best thing is to test conformance, as you've started to do:

#if __cplusplus < 201103L
#error This source must be compiled as C++11 or later
#endif

That ensures that compilation with a C++03 compiler will give a simple, understandable error message straight away.

Upvotes: 6

YSC
YSC

Reputation: 40100

Is it possible to set g++ to follow C++11 ISO (-std=c++11) through #define?

No.

Neither C++ nor g++ have that feature. You might want to build simple one-file programs manually.

Upvotes: 3

gsamaras
gsamaras

Reputation: 73394

No.

You shouldn't changing the #define __cplusplus. Read more in How to trigger the __cplusplus (C++) #ifdef?, because __cplusplus should be automatically defined by C++ compiler. That's why changing the version is meant to be done via the compiler settings.

It doesn't make sense to have a file follow C++11, while the others would follow C++14, for example. The whole project should be compiled in a homogeneous way.

Notice that your code wouldn't compile: Error: macro names must be identifiers using #ifdef 0.

PS: What a nightmare it would be in terms of readability and maintenance if what you described was a good idea..

Upvotes: 1

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