Square of a number being defined using #define

Question

I was just going through certain code which are frequently asked in interviews. I came up with certain questions, if anyone can help me regarding this?

I am totally

Answer 1

Because of operator precedence in the expression after the preprocessor - you'll need to write

#define square(x) (x*x)

Answer 2

i=4/square(4);

expands to

i=4/4*4; 

which equivalent to

i=(4/4)*4;

Answer 3

That's because the compiler replaces it with:

i=4/4*4; 
j=64/4*4;

i = (4/4)*4 = 1*4 = 4.

j = (64/4)*4 = 16*4 = 64.

Answer 4

Manually expand the macro in the code, and it will be clear. That is, replace all the square(x) with exactly x*x, in particular don't add any parentheses.

Answer 5

As the other answers say, you're getting burned by operator precedence. Change your square macro to this:

#define square(x) (x*x)

and it'll work the way you expect.