reverse an integer

int reverse(int num)  //works only for non neg numbers
{
  if(num < 0)
  {
     System.out.println("does not work for neg integers");
     return -1;
  }

  int rev = 0;
  while(num > 0)
  {
     rev = rev * 10 + num%10;
     num /= 10;
  }

  return rev;
}

can be used to check if a given number is palindrome.