[C++] Codice della funzione itoa()

[oregon]

Puo' differire leggermente a seconda delle implementazioni ... un esempio e' questo

char * __cdecl _itoa (int val, char *buf, int radix)
{ 
  if (radix == 10 && val < 0)
    xtoa((unsigned long)val, buf, radix, 1);
  else
    xtoa((unsigned long)(unsigned int)val, buf, radix, 0);

  return buf;
}

e la funzione xtoa e'

static void __cdecl xtoa (unsigned long val, char *buf, unsigned radix, int is_neg)
{
  char *p;                /* pointer to traverse string */
  char *firstdig;         /* pointer to first digit */
  char temp;              /* temp char */
  unsigned digval;        /* value of digit */

  p = buf;

  if (is_neg)
  {
    /* negative, so output '-' and negate */
    *p++ = '-';

    val = (unsigned long)(-(long)val);
  }

  firstdig = p;           /* save pointer to first digit */

  do
  {
    digval = (unsigned) (val % radix);

    val /= radix;       /* get next digit */

    /* convert to ascii and store */
    if (digval > 9)
      *p++ = (char) (digval - 10 + 'a');  /* a letter */
    else
      *p++ = (char) (digval + '0');       /* a digit */
  } while (val > 0);

  /* We now have the digit of the number in the buffer, but in reverse
           order.  Thus we reverse them now. */

  *p-- = '\0';        /* terminate string; p points to last digit */

  do
  {
    temp = *p;
    *p = *firstdig;
    *firstdig = temp;   /* swap *p and *firstdig */
    --p;
    ++firstdig;         /* advance to next two digits */
  } while (firstdig < p); /* repeat until halfway */
}