ex-3-4.c

/*
 * Exercise 3-4. In a two's complement number representation, our version of 
 * itoa does not handle the largest negative number, that is, the value of n 
 * equal to -(2^wordsize - 1). Explain why not. Modify it to print that value 
 * correctly, regardless of the machine on which it runs.  
 */

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

#define abs(x) ((x) < 0 ? -(x) : (x))

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

void itoa(int n, char s[])
{
	int i, sign;

	sign = n;
	i = 0;
	do {
		s[i++] = abs(n % 10) + '0';
	} while ((n /= 10) != 0);
	if (sign < 0)
		s[i++] = '-';
	s[i] = '\0';
	reverse(s);
}

int main(void)
{
	char s[20];
	printf("INT_MIN = %d\n", INT_MIN);
	itoa(INT_MIN, s);
	printf("INT_MIN = %s\n", s);
	return 0;

}