十六進位轉換（內建）

我把那個function貼過來
到今天我才知道，當你叫一個printf時候
他真的去call很多function的說 好複雜呀
我有把轉換的地方標出來了

static char *number(char *str, long num, int base, int size, int precision, int type)
{
  char c, sign, tmp[66];
  char *dig = digits;
  int i;

  if (type & LARGE)  dig = upper_digits;
  if (type & LEFT) type &= ~ZEROPAD;
  if (base < 2 || base > 36) return 0;
  
  c = (type & ZEROPAD) ? '0' : ' ';
  sign = 0;
  if (type & SIGN)
  {
    if (num < 0)
    {
      sign = '-';
      num = -num;
      size--;
    }
    else if (type & PLUS)
    {
      sign = '+';
      size--;
    }
    else if (type & SPACE)
    {
      sign = ' ';
      size--;
    }
  }

  if (type & SPECIAL)
  {
    if (base == 16)
      size -= 2;
    else if (base == 8)
      size--;
  }

  i = 0;

  if (num == 0)
    tmp[i++] = '0';
  else
  {
    while (num != 0)
    {
      tmp[i++] = dig[((unsigned long) num) % (unsigned) base];
      num = ((unsigned long) num) / (unsigned) base;
    }
  }

  if (i > precision) precision = i;
  size -= precision;
  if (!(type & (ZEROPAD | LEFT))) while (size-- > 0) *str++ = ' ';
  if (sign) *str++ = sign;
  
  if (type & SPECIAL)
  {
    if (base == 8)
      *str++ = '0';
    else if (base == 16)
    {
      *str++ = '0';
      *str++ = digits[33];
    }
  }

  if (!(type & LEFT)) while (size-- > 0) *str++ = c;
  while (i < precision--) *str++ = '0';
  while (i-- > 0) *str++ = tmp[i];
  while (size-- > 0) *str++ = ' ';

  return str;
}