Question

I have to write a code that can support newer and older compilers and i was wondering before i start is something like this possible?

#ifndef C++11 { //some code..... } 
#endif 

else 

#ifndef older C++ version { //some code......}
#endif

Answer 1

The standard requires C++11 conforming implementations to define a macro named __cplusplus to the value 201103L. Nonconforming compilers are recommended to use a value with at most five decimal digits. The same was true for C++03 where the value this should be defined to is 199711L.

However, not many compilers consider(ed) themselves standards compliant, and e.g. gcc defined this for a long time to be just 1L. Also you have to consider that it is not only the compiler version, but also the parameters to the compiler. Gcc only supports (part of) C++11 when you pass -std=c++0x or -std=gnu++0x. In these cases it will define a macro __GXX_EXPERIMENTAL_CXX0X__.

So the most portable solution is to be unportable and have your own macro that you set when C++11 support is detected, and have some header/configure script in which you use the aforementioned things, along with possibly others for other supported compilers.