Can anyone explain this code please ?

Question

#include<stdio.h>

#define macro(r,a,b) b##a##r

#define CHAOS macro(r,a,b)

void CHAOS(int n){printf("%d",n);}

int main(){

    bar(4);

    bar(2);

    return 0;

}

Answer 1

#define is a pre-processor directive first CHOAS is replaced by macro(r,a,b)
Again we have another #define it replaces macro(r,a,b) by b##a##r
## acts as token pasting operator
So b##a##r=bar
Hence void CHOAS(int n) is void bar(int n)
bar(4);//outputs 4
bar(2);//outputs 2
So,final output is 42

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