Question

How to use #define DEBUG in C

Answer 1

#include <stdio.h>

#define DEBUG

int main(void)
{
    printf("main start\n");

    #ifdef DEBUG
        printf("DEBUG\n");
    #endif

    printf("main end\n");

    return 0;
}




/*
run:

main start
DEBUG
main end

*/

 

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Answer 2

#include <stdio.h>

#define DEBUG

int main()
{
    #ifdef DEBUG
        printf("DEBUG is on\n");
    #endif

    #ifndef DEBUG
        printf("DEBUG is off\n");
    #endif

    return 0;
}




/*
run:

DEBUG is on

*/

 

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