My favorite Pre-processor hackery

for shortcut

#include <stdio.h>

#define to ; i <=
#define DO(range) for(int range; i++) 


int main()
{
    int arr[10];
    DO(i = 0 to 9)
      arr[i] = 2 * i;
    
    DO(i = 0 to 9)
      printf("%d\n", arr[i]);

    return 0;
}