Program to convert a base 10 integer to base 2, 8 and 16.

changebase.c

/**
* File: 7.7.c
* Author: Santosh Kumar <sntshkmr60@gmail.com>
* Date created: Tue 08 Oct 2013 06:33:28 IST
* Description: Program to convert a positive integer to another base
* Taken from 'Programming in C' book.
*/

#include <stdio.h>

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

    int convertedNumber[64];
    long int numberToConvert;
    int nextDigit, base, index = 0;

    // get the number and the base

    printf("Number to be converted? ");
    scanf("%ld", &numberToConvert);
    printf("Base? ");
    scanf("%i", &base);

    // convert to the indicated base

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

    // display the result in reverse order

    printf("Converted number = ");

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

    printf("\n");
    return 0;
}