Printing Bits

makefile

CC = gcc
CFLAGS = -I.

test: main.o
	$(CC) -o $@ $(CFLAGS) main.o
	

main.o: main.c
	$(CC) -c main.c $(CFLAGS)

printingbits.c

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

#define BITS_PER_BYTE 8

int main(int argv, char *argc[])
{
	if(!argc[1]){
		printf("Positive integer input required.\n");
		exit(1);
	}

	const int SHIFT = BITS_PER_BYTE * sizeof(unsigned) - 1;
	unsigned value = atoi(argc[1]);
	const unsigned MASK = 1 << SHIFT;

	int i;

	for(i = 1; i <= SHIFT + 1; i++) 
	{
		printf("%c",( value & MASK ? '1' : '0' ));
		value <<= 1;
		if ( i % 8 == 0 )
			printf(" ");
	}

	printf("\n");

	return 0;
}