C_PRG_LANG_EX_3.6

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <limits.h>

#define ABS(n) n >= 0 ? n : -n

void reverse(char *s)
{
    char *end = s;

    while (*end)
        end++;
    end--;

    while (end > s)
    {
        char tmp = *end;
        *end-- = *s;
        *s++ = tmp;
    }

    return;
}

void my_itoa_v2(int numb, char *s, int min_len)
{
    int sign = 0;
    if (numb < 0)
        sign++;

    char *start = s;
    do
    {
        int digit = (numb % 10);
        digit = ABS(digit);
        *s++ = digit + '0';
        numb /= 10;
    } while(numb);

    if (sign)
        *s++ = '-';

    for(char *ptr = start; ptr != s; ptr++)
        min_len--;

    for(int i = 0; i < min_len; i++)
        *s++ = ' ';

    *s = '\0';

    reverse(start);

    return;
}

int main(void)
{
    srand(time(NULL));
    char str[256];

    my_itoa_v2(INT_MIN, str, 20);
    printf("for numb %i and min length %i result is:\n%s\n\n",
           INT_MIN, 20, str);

    my_itoa_v2(INT_MAX, str, 20);
    printf("for numb %i and min length %i result is:\n%s\n\n",
           INT_MAX, 20, str);
    for (int i = 0; i < 10; i++)
    {
        int numb = rand();
        int gape = rand() % 10;
        my_itoa_v2(numb, str, gape);
        printf("for numb %i and min length %i result is:\n%s\n\n",
               numb, gape, str);
    }
    return 0;
}