Question

#include<stdio.h>
#include<stdlib.h>

#define d 10+10

int main()
{
    printf("%d",d*d);
return 0;
}

I am new to the concept of macros.I found the output for the above program to be 120.What is the logic behind it?

Thanks.

Answer 1

Macros are replaced literally. Think of search/replace. The compiler sees your code as 10+10*10+10.

It is common practice to enclose macro replacement texts in parentheses for that reason:

#define d (10 + 10)

This is even more important when your macro is a function-like macro:

#define SQ(x) ((x) * (x))

Think of SQ(a + b)…