Help with macros

[Yadav]

Hi guys,
             I was working on macros and I am curious abt the result of the sample program below. The result (Product) of the program is 7, I was expecting 16. If I change the code to Product(x) then it wrks fine. I wanted to know wt happens if the argument to the macros is Product(x+1). Please help!!!!!!


#include<stdio.h>

#define PRODUCT(x) (x*x)

int main(void)
{
   int i=6,j;

   j=PRODUCT(i+1);    //Dono how it is processed???
   printf("Product=%d\n",j);

   return 0;
}

[frankie]

For i=3 (not 6 as you wrote) you expected 16 as result, but got 7 because there are no parenthesis in the macro.
Macro substitution is a 'literal' substitution so X*X when x=i+1 gives i+1*i+1=3+1*3+1=7 
If you write your macro as:

Code: [Select]

#define PRODUCT(x) ((x)*(x))then you will get X*X => (i+1)*(i+1)=(3+1)*(3+1)=4*4=16....

[Yadav]

Ya got it....Rookie mistake:-[ .