/* Convert decimal to binary. uses bit functions and MASKs
*/
#include <stdio.h>
#define MASK1 0x0001
char binchars[32];
unsigned xin;
int nbits, i, xbit;
int binary();
int readyn();

main()
{
	unsigned xin;
	
	do{
		printf("enter number [decimal int]: ");
		scanf("%d",&xin);
		binary(xin);
		printf("convert another ");
	}
	while(readyn());

}


int binary(xin)
	unsigned xin;
{
	int nbits, i, xbit;
	char binchars[32];
	
	nbits = 8*sizeof(xin);
	xbit = xin;
	
	for (i=0;i<nbits;i++){
		
		if((xbit & MASK1) == 1){
			binchars[i] = '1';
		}
		else{
			binchars[i] = '0';
		}

		xbit = ( xbit >> 1 );
	}

	printf("xin = %d decimal, %u unsigned, %x hex, ",xin,xin,xin);

	for(i=nbits-1;i>=0;i--){

		printf("%c",binchars[i]);

	}

	printf(" binary\n\n");

}

int readyn()
/* returns 1 for TRUE, 0 for FALSE, -1 on error */
{
	char yn[2];

	do{
		printf(" [Y/N] ? ");
		scanf("%1s",yn);
	}
	while ( !( (yn[0] == 'Y') || (yn[0] == 'y') ||
	 	   (yn[0] == 'N') || (yn[0] == 'n') ) );
	
		switch (yn[0]){
	
		case 'Y' :
		case 'y' :
			return(1);	

		case 'N' :
		case 'n' :
			return(0);

		default:
			return(-1);

		}
}