/* Exercise 3.5 from "The C programming language" book by K&R */

#include <stdio.h>
#include <string.h>

void reverse(char s[])
{
	int c, i, j;
	for (i = 0, j = strlen(s)-1; i < j; i++, j--) {
		c = s[i];
		s[i] = s[j];
		s[j] = c;
	}
}

/* converts integer n to it symbol representation in
scale of notation with b radix, and put result to s[] */
void itob(char n, char s[], char b)
{
    static char digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	char sign;
	char i;

	if ((sign = n) < 0)
        n = -n;
    i = 0;
    do
		s[i++] = digits[n % b];
    while ((n /= b) > 0);
    if (sign < 0)
        s[i++] = '-';
    s[i] = '\0';
    reverse(s);	
}

int main(void)
{
	char s[100] = "";
	itob(123,s,16);
	printf("%s\n",s);
	return 0;
}