Hello. I'm currently a 10th grader who's been sitting in front of the computer for hours trying to figure this assignment out. First, my teacher gave me a reverse integer problem. He wants us to reverse the numbers 12345, 10001, 1200, and 5, and display in in the output. The leading zeros can be omitted. I got the method down here (for the first integer):

    //initialize
    int tmpInt1 = 0;

    while(tmpInt1 == 12345) 
    {
        newInt *= 10;
        newInt += tmpInt1 % 10;
        tmpInt1 /= 10;
    }

However, there seems to be a problem displaying it in the output, which looks like this:

    FunLoops fun = new FunLoops();
    System.out.println("12345 reversed ---> " + fun.reverse(12345));

That's just the first reverse integer, and I am clueless on how to add the other numbers in. Should I use a nested loop? If so, how should I use it? After I figure this out, I still need to do the LCM and the Magic Square part, which is even more complicated. I'm glad I have a 4-day weekend, so this isn't that urgent. But I still need the help. Can someone please show me the correct way to do this? Thank you all so much!!!

Edited 3 Years Ago by pyTony: fixed formating

>I got the method down here (for the first integer):
Why not write it generally for all integers?

public int reverse_integer ( int val )
{
  int ret = 0;

  while ( val != 0 ) {
    ret = 10 * ret + ( val % 10 );
    val /= 10;
  }

  return ret;
}

>I am clueless on how to add the other numbers in.
It's easiest just to call reverse for each number, provided that reverse can handle any integer intelligently:

System.out.println("12345 reversed ---> " + fun.reverse(12345));
System.out.println("12345 reversed ---> " + fun.reverse(10001));
System.out.println("12345 reversed ---> " + fun.reverse(1200));
System.out.println("12345 reversed ---> " + fun.reverse(5));

Thank you, Narue! This portion of the program is working now! :)

Hopefully, I'm not asking too much, but there's just one last thing I need, and that is how to figure out the LCM of two numbers. I don't really know how to approach it. Should it be best if I stick with using a while loop, compare the two integers, and increment it until it finds the LCM, or should I do something else?

Calculating the least common multiple is trivial if you have a routine to find the greatest common divisor:

public int lcm ( int a, int b )
{
  return a * b / gcd ( a, b );
}

You shouldn't have any trouble finding out the algorithm for finding the greatest common divisor, it's everywhere. :)

class ReverseTest {

public static void main(String[] args) {

int originalInt = 12345;
int reversedInt = 0;

// convert Integer value to String. Strings can be easily reversed
String intToString = new Integer(originalInt).toString();

//Create a StringBuffer from the original string
StringBuffer buffer = new StringBuffer(intToString);

//Reverse the contents of the StringBuffer
buffer = buffer.reverse();

// convert String back to integer
reversedInt = Integer.parseInt(buffer.toString());


// print out the result
System.out.println("Reversed Integer: " + reversedInt);

} // main

}

I bet the OP has been waiting impatiently for the 7 1/2 years since he posted and then solved this problem, just in case you would come along with another solution. That's great. He can hand his homework in now.

This question has already been answered. Start a new discussion instead.