What is the correct way to define this C macro? -

#include <stdio.h> #define abs(a)  (a) < 0 ? -(a) : (a) int main(void) {   printf("%d\n", abs(-3) + 1);   return 0; } 

this code snippet, herbert schildt's book, looks produce output 4 prints 3. why?

how fix it?

expand macro:

#define abs(a)  (a) < 0 ? -(a) : (a)  printf("%d\n", abs(-3) + 1);  printf("%d\n", (-3) < 0 ? -(-3) : (-3) + 1); // can **gcc -e source.c  printf("%d\n", (-3) < 0 ? 3 : -2); //read precedence understand step.  printf("%d\n", 3); 

this step step explanation of why printing 3. need fix using appropriate parenthesis.