Messing around with a fun fact. Since unsigned integers wrap around, you are able to do modulo arithmetic implicitly for common sizes of 2^n, where n =128 (signed chars), 256 (unsigned chars), 65536 ( short int), and etc for long doubles and other types.

mod2powers.c

#include <stdio.h>


/*
Fun Fact:
 Using an unsigned integer causes integer arithmetic module 2^n where n is the number of bits in the type
*/
main(){
	unsigned char mod256;
	mod256 = 16*18;
	//Generates a warning: 
	//warning: large integer implicitly truncated to unsigned type [-Woverflow]
	//16*18 = 288
	//16*18 % 256 == 32
	printf("16*18 mod 256 = %d\n", mod256);

	unsigned short int mod65536;
	//A useful thing to do is work in 16 bit archectures. And to remember you're working modulo
	//2^16 + 1  == 1
	mod65536 = 16*16*16*16+1;
	printf("2^16 + 1  mod 2^16 = %d\n", mod65536);

	//Dirty way of computing the max size of an unsigned integer
	unsigned long int howBigsALong;
	howBigsALong = -1;
	printf("An unsigned long can be %lu large\n", howBigsALong);

	//Using howBigsALong to determine the power of two representation
	int i;
	for(i = 0; howBigsALong != 0; i++){
		howBigsALong = howBigsALong/2;
	}
	printf("A long is (2^%d)-1 big\n", i );

	//how big is a really long long?
	unsigned long long int biglon;
	biglon = -1;


	unsigned long long int low;
	unsigned long long int high;
	low = biglon;
	high = (biglon >> 64);
	//Print in hex because otherwise things get cimplicated
	printf("This long is pretty big, its: 0x%llx%llx big! \n", high,biglon);
	//and in 2^n
	for(i=0; biglon != 0; i++){
		biglon = biglon/2;
	}
	printf(" or (2^%d)-1\n",i*2);




	
}