Why are preprocessor macros evil and what are the alternatives?

Question

I have always asked this but I have never received a really good answer; I think that almost any programmer before even writing the first \"Hello World\" had encountered a p

Answer 1

Macros in C/C++ can serve as an important tool for version control. Same code can be delivered to two clients with a minor configuration of Macros. I use things like

#define IBM_AS_CLIENT
#ifdef IBM_AS_CLIENT 
  #define SOME_VALUE1 X
  #define SOME_VALUE2 Y
#else
  #define SOME_VALUE1 P
  #define SOME_VALUE2 Q
#endif

This kind of functionality is not so easily possible without macros. Macros are actually a great Software Configuration Management Tool and not just a way to create shortcuts for reuse of code. Defining functions for the purpose of reusability in macros can definitely create problems.