ex.8.16.c

// Program to convert a positive integer to another base

#include <stdio.h>

int			convertedNumber[64];
long int	numberToConvert;
int			base;
int			digit;

void getNumberAndBase (void)
{
	printf ("Number to be converted? ");
	scanf  ("%li", &numberToConvert);

	if ( numberToConvert != 0 ) {
		printf ("Base? ");
		scanf  ("%i", &base);

		if ( base < 2 || base > 16 ) {
			printf ("Bad base - must be between 2 and 16\n");
			base = 10;
		}
	}
}

void convertNumber (void)
{
	do {
		convertedNumber[digit] = numberToConvert % base;
		++digit;
		numberToConvert /= base;
	}
	while ( numberToConvert != 0 );
}

void displayConvertedNumber (void)
{
	const char baseDigits[16] =
		   { '0', '1', '2', '3', '4', '5', '6', '7',
			 '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
	int nextDigit;

	printf ("Converted number = ");

	for ( --digit; digit >= 0; --digit ) {
		nextDigit = convertedNumber[digit];
		printf ("%c", baseDigits[nextDigit]);
	}

	printf ("\n");
}

int main (void)
{
	void getNumberAndBase (void), convertNumber (void),
		 displayConvertedNumber (void);

	while ( 1 ) {
		digit = 0;
		getNumberAndBase ();
		if ( numberToConvert == 0 )
			break;

		convertNumber ();
		displayConvertedNumber ();
	};

	return 0;
}