/*
 * Program to show bit representation of long int, two ways --
 * as a long int, and as a sequence of bytes
 */
#include <stdio.h>
#include <limits.h>

void show(long n);
void show_using_union(long n);
void showbyte(unsigned char b);

int main(void) {
	long n;
	puts("enter integer");
	if (scanf("%ld", &n) != 1) { puts("invalid input") ; return 1; }
	printf("%ld considered as long:\n", n);
	show(n);
	printf("%ld considered as sequence of bytes:\n", n);
	show_using_union(n);
	return 0;
}

/* 
 * show bit representation of n, treating it as a long 
 */
void show(long n) {
	unsigned char byte_mask = ~((unsigned char) 0);
	for (int byte_index = 0; byte_index < sizeof(n); ++byte_index) {
		unsigned char b = 
			(n >> (sizeof n - 1 - byte_index)*CHAR_BIT) & byte_mask;
		showbyte(b);
		putchar(' ');
	}
	putchar('\n');
}

/* union to allow viewing "long" as sequence of bytes */
typedef union {
	long n;
	unsigned char bytes[sizeof(long)];
} long_bytes_t;

/* 
 * show bit representation of n, treating it as a sequence of bytes 
 */
void show_using_union(long n) {
	long_bytes_t work;
	work.n = n;
	for (int i = 0; i < sizeof(n); ++i) {
		showbyte(work.bytes[i]);
		putchar(' ');
	}
	putchar('\n');
}

/* show byte as bits */
void showbyte(unsigned char b) {
	for (unsigned char mask = 1 << (CHAR_BIT-1); mask > 0; mask >>= 1) {
		if ((mask & b) > 0)
			putchar('1') ;
		else 
			putchar('0');
	}
}