Find output of following c program

Question

What is the output of the following $C$ code segment?

# define product (a, b) a * b 
main() 
{ 
  int x=5, y=2;
  print f("%d", product{x+4, y-3}); 
}

1. $10$
2. $-9$
3. $15$
4. Error.

Answer 1

because MACRO product expands like this -

product(x+4,y-3) expands to  x + 4 * y - 3 => 5 + 4 * 2 - 3 => 5 + 8 - 3 =>10 (ANS)

Answer 2

follow the operator precedence rules . you will get ans 10. Product(x+4,y-3) expands to x + 4 * y - 3 => 5 + (4 * 2) - 3 => (5 + 8) - 3 =10.
Instead of macro if you had used normal function like this
int product(int a, int b)
 {
     return a*b;
 }
then the answer will be -9

Comments

if we pass values to a function which are in form of expression then it will be evaluated while in case of macro's expression is directly passed ????? is that right???

Answer 3

In C macro expands without any Braces or Parenthesis so here macro(a,b)= like a*b

put whatever is in a or b without any brackets or something like that

here (x+4) and (y-3) are given so macro expansion

X+4*Y-3

now by precedence and associativity at first * will be computed then + and-

so 5+4*2-3=13-3=10

 

A is correct answer