Thread: Need help with YES/NO Loop in Fibonacci Sequence

Using a while loop, the general form is:

while ( again )
{
    // the code to repeat
 
 
    // ask the user if the loop should repeat,
    // if yes, again stays true
    // if no, again = false.
 
}

The same can be done with a do/while loop.

Yeah...

I heard of this, but...

How can I make it work for a YES/NO Loop?

If I choose yes, how will it do it again?

I'm very confused.

Can anyone show me how?

You can use my code if you want for example.

There's no such thing as a "YES/NO Loop" in Java.

If I choose yes, how will it do it again?

By using an if statement to set a flag ('again' in my example) that indicates whether the loop will repeat. My example does everything but write the code for you. Why don't you try filling in the code and then come back with code when you need help.

Close.

while (again = true)

'=' is an assignment operator. Further, a comparison using a boolean is unnecessary simply:

while ( again )

will do (as I showed originally).

Then,

System.out.print("Would you like to try again?");

You already have a Scanner object with which to collect input from the user/console. Do that to get the answer to the above question, then use the if statement I described to set the 'again' flag.

This is getting very confusing.

Please... can you show me how to do just that by using my code?

Not just show me the little parts?

Here's another helpful tip: I want to be able to input 1 for YES or 2 for NO.

Little details like using 1 or 2 instead of YES/NO are fundamental to the design, not helpful tips.

This is nothing you can't do, but here's an elementary example. You can figure out how to change the code to use 1/2 versus Y/N:

import java.util.Scanner;
 
// a simple class to demonstrate a while loop that repeats
// according to the user's selection
public class WhileLoopExample
{
    public static void main( String[] args )
    {
        boolean again = true;
        Scanner getInput = new Scanner( System.in );
 
        while ( again )
        {
            // add code to repeat here
            System.out.println( "In the loop." );
 
            // gathers the user's input to determine if the loop
            // should repeat. does NOT include input verification or any
            // other error checking
            System.out.print( "Would you like to calculate another"
                + " value? (Y/N) " );
            String answer = getInput.nextLine();
 
            if ( answer.equalsIgnoreCase( "N" ) )
            {
                again = false;
            }
        }
 
        System.out.println( "Thanks for playing!" );
 
    } // end method main()
 
} // end class WhileLoopExample

Thank you.

I will try it out.

--- Update ---

Sorry for double posting, but...

 
public class FibSeqByIanNeumann {
 
    public static void main(String[] args) {
 
        Scanner get = new Scanner(System.in);
        Scanner input = new Scanner( System.in );
        boolean again = true;
        int ctr, num1, num2, fib, maxTimes;
 
        while ( again ) //loops again if user inputs Y for yes.
        {
 
        System.out.print("\n" + "How many sequences do you want?: ");
        maxTimes = get.nextInt(); //inputs the maxium limit of the fib sequence
 
        num1 = 0; //This is the part to get the fib sequence to start at 0!
        num2 = 1; //helps to add up the fib sequence numbers.
        fib = 0;
 
        System.out.print("\n" + "When a fibonacci sequence runs for " + maxTimes
                + " times, it looks like this: " + "\n");
 
        System.out.print("\n" + num1);
        System.out.print(", " + num2);
 
        for (ctr = 0; ctr <= maxTimes - 3; ctr++) 
        {
 
            fib = num1 + num2;
            num1 = num2;
            num2 = fib;
 
            System.out.print(", " + fib);
 
        }
 
        System.out.print("\n" + "\n");
 
            System.out.print("Would you like to try another sequence?" + "\n"); //asks user for another sequence.
            System.out.print("Input Y for Yes or N for No: "); //information for user
            String answer = input.nextLine(); //inputs answer for YES or NO.
 
            if ( answer.equalsIgnoreCase( "N" ) ) //If the answer is N or no...
            {
                again = false;
            }
 
        }
 
        System.out.println("\n" + "''That's all Folks!''" + "\n");  //...this happens.
 
    } 
}

It is... done.

I'll leave this code up for future references.

Oh (disappointed). You couldn't figure out how to do 1/2?

Nah... this actually quite helped.

Okay then. Glad to help.