Strange behaviour of macros C/C++

Question

I\'m using some macros, and observing some strange behaviour.

I\'ve defined PI as a constant, and then used it in macros to convert degrees to radians and radians to

Answer 1

Macros are (relatively simple) textual substitutions.

Use parentheses in your definitions (both to enclose the macro itself and the macro arguments):

#define PI (atan(1) * 4)
#define radians(deg)  ((deg) * PI / 180)
#define degrees(rad)  ((rad) * 180 / PI)