Loop question

[rich123]

Hey all.

I been given this code:-

import java.util.*;

public class Syr {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int x;

		System.out.println("Enter a number to be iteratively mapped using the Syracuse function.");
		do {
			System.out.println("(Please make sure it is greater than 1.)");
			x = sc.nextInt();
		} while (x <= 1);

		System.out.print(x);
		do {
			if ((x % 2) == 0)
				x = x / 2;
			else
				x = 3 * x + 1;
			System.out.print("->" + x);
		} while (x != 1);
		System.out.println();
		System.out.println("Our hypothesis is true for this value!");
	}
}

Its asks how would the second loop change if the program allowed the x to be 1.
I thought that it could possibly be that change

while (x != 1);

to

while (x >=1);

but it just produces a line of 1->4->2 without stopping.

Any help appreciated! :)

[quad64bit]

Your code works for me, you sure?
x = 1
result:
->4->2->1
x = 3
result:
->10->5->16->8->4->2->1
x = 4
result:
->2->1

[rich123]

What code did you use?

Code I tried using:

import java.util.*;

public class Syr {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int x;

		System.out.println("Enter a number to be iteratively mapped using the Syracuse function.");
		do {
			System.out.println("(Please make sure it is greater than 1.)");
			x = sc.nextInt();
		} while (x <= 0);

		System.out.print(x);
		do {
			if ((x % 2) == 0)
				x = x / 2;
			else
				x = 3 * x + 1;
			System.out.print("->" + x);
		} while (x >=1);
		System.out.println();
		System.out.println("Our hypothesis is true for this value!");
	}
}

This just prints = 1->4->2 repeatedly until i terminate the program, I dont know if im missing something?

Thanks

[quad64bit]

int x = 7;
do {
    if ((x % 2) == 0)
        x = x / 2;
    else
        x = 3 * x + 1;
    System.out.print("->" + x);
} while (x >=1);

I assigned values to x manually.

[quad64bit]

I also suggest you clean and rebuild your program. Especially in eclipse, sometimes, it gets the current code and last build confused and executes some old version of the project.

[Junky]

I'm not sure what code you are running quad but if you change the condition to x >= 1 then it becomes an endless loop.

Why? If you examine the if statement carefully you will see that it is impossible for x to ever be less than 1.

[quad64bit]

You know, I don't know what I ran either. I must have fixed it by accident when I pasted it in. I'm sorry! :P