Note to self – subtracting unsigned integers

I was having a small Arduino problem this weekend involving counters so had to do some research on subtracting unsigned integers from one another in the context of counter rollover. Interesting solution to that problem using modulus UINT_MAX+1. Thank you to this answer on Stackoverflow.com (Is unsigned integer subtraction defined behavior?). Below is my test code.

#include <stdio.h>

unsigned char counter = 0;
unsigned char previousCounter = 0;
unsigned int interval=47;

int main () {
   for (int x=0; x= interval) { // check for rollover
         printf("Reached interval at %d (%d), %d n",
            currentCounter, previousCounter, (unsigned char)(currentCounter - previousCounter));
         previousCounter = currentCounter;
      }
   }
}