What should be the precautions we should take while writing the preprocessor statement i.e. #define in C?

Question

Lot of confusion and lot of scattered info, can someone help me by providing to the point response.

Answer 1

I saw only two use of #define. First it is used to define constant and second to define macro function.

1. When macro should be defined before it's uses start.
2. Some macros are already defined by compiler, avoid to redefine them.
3. Take care of parenthesis while defining macro function.

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