Macro Constants

Object-like macros name compile-time constants before the compiler sees the program.

macro_constants.c

#include <stdio.h>

#define TAX_RATE 8

int main(void) {
    int price = ;
    int taxRate = 8;
    int tax = price * taxRate / 100;
    int total = price + tax;

    printf("total=%d\n", total);
    return 0;
}

#include <stdio.h>

#define TAX_RATE 8

int main(void) {
    int price = ;
    int taxRate = 8;
    int tax = price * taxRate / 100;
    int total = price + tax;

    printf("total=%d\n", total);
    return 0;
}

#include <stdio.h>

#define TAX_RATE 8

int main(void) {
    int price = ;
    int taxRate = 8;
    int tax = price * taxRate / 100;
    int total = price + tax;

    printf("total=%d\n", total);
    return 0;
}

object-like macro The preprocessor replaces a macro name with its replacement text before parsing.

runtime use The trace uses the expanded value so the replay stays aligned with source lines.