Working of the C Preprocessor

Question

How does the following piece of code work, in other words what is the algorithm of the C preprocessor? Does this work on all compilers?

#include 

        

Answer 1

#define simply assigns a value to a keyword.

Here, 'b' is first assigned value 'a' then 'a' is assigned value '170'. For simplicity, it can be expressed as follows:

b=a=170

It's just a different way of defining the same thing.