#define used with operators [duplicate]

Answer 1

macros in c/c++ are just text substitutions, not functions. So the macro is there just to replace a macro name in the program text with its contents before the compiler event tries to analyze the code. So in the first case the compiler will see this:

BETA ==> ALPHA * 2 ==> 2 - 1 * 2 ==> compiler ==> 0
printf("beta=%d\n", BETA); ==> printf("beta=%d\n", 2 - 1 * 2);

In the second

BETA ==> ALPHA * 2 ==> (2 - 1) * 2 ==> compiler ==> 2
printf("beta=%d\n", BETA); ==> printf("beta=%d\n", (2 - 1) * 2);