Protected blocks in C

protected.c

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

// Make sure that before is executed before a dependent block or statement
// and after is executed afterwards
#define PROTECTED(before, after) \
    for (int __i = ((before), 0); !__i; (after), __i++)

int main(void)
{
    int i, sum = 0;

#define N 100

    PROTECTED(assert(sum == 0), assert(sum == N*(N+1)/2)) {
        for (i = 1; i <= N; i++) {
            sum += i;
        }
    }

    return 0;
}