How to define C++ preprocessor variable in Makefile

Question

I have a C++ preprocessor written like this:

  #ifdef cpp_variable
   //x+y;
  #endif

Can anyone tell me how to define this in Makefile.

Answer 1

Search your compiler documentation to find how to do that.

For example for g++ the syntax is :

g++ -Dcpp_variable 

Which corresponds to adding

CPPFLAGS += -Dcpp_variable

in your makefile.