Backwards for loops

reverse_for.c

//usr/bin/gcc -Wall -Wextra -Wpedantic -Wconversion -std=c99 reverse_for.c -o reverse_for && ./reverse_for
// https://github.com/zbanks
#include <stdio.h>

#define for(BODY) for2(__COUNTER__, _count, _i, BODY)
#define for2(_uniq, _count, _i, BODY) for3(_uniq, _count, _i, BODY)
#define for3(_uniq, _count, _i, BODY) for4(_count ## _uniq, _i ## _uniq, BODY)
#define for4(_count, _i, BODY) \
    long _count = 1; \
    for (BODY) _count++; \
    for (long _i = 1; _count; _count--, _i = 1) \
        for (BODY) \
            if (_i++ == _count)


int main(void) {
    // Prints "9 8 7 6 5 4 3 2 1 0"
    for (int i = 0; i < 10; i++) {
        printf("%d ", i);
    }
    printf("\n");

    // Prints "!dlrow ,olleH"
    const char * string = "Hello, world!";
    for (const char * ptr = string; *ptr; ptr++) {
        printf("%c", *ptr);
    }
    printf("\n");
    
    return 0;
}