Converting for loop to while loop in Java

Question

I need to convert this for loop into a while loop so I can avoid using a break.

double[] array = new double[100];

Scanner scan = new Scanner(System.in); 

for (int index = 0; index < array.length; index++)
    {
        System.out.print("Sample " + (index+1) + ": ");
        double x = scan.nextDouble();
        count++;
        if (x < 0) 
        {
            count--;
            break;
        }
        array[index] = x; 
    }

This is what I came up with but I'm getting a different output:

int index = 0;

double x = 0; 

while (index < array.length && x >= 0)
    {
        System.out.print("Sample " + (index+1) + ": ");
        x = scan.nextDouble();
        count++;
        if (x < 0) 
        {
            count--;
        }
        array[index] = x;
        index++;
    }

Excuse me, but why in God's name would you 1) want to use while instead of for, and 2) avoid break? Usually those two intentions make your code a lot harder to read... — JayC667
– JayC667, Commented Dec 9, 2015 at 3:23

gooeyn · Accepted Answer · 2015-12-09 00:03:40Z

1

this solution gives the same output as the for loop:

while (index < array.length && x >= 0)
{
    System.out.print("Sample " + (index+1) + ": ");
    x = scan.nextDouble();
    count++;
    if (x < 0) 
    {
        count--;
    }
    else
    {
        array[index] = x;
        index++;
    }
}

EXPLANATION:

On the for loop you use the break statement so nothing happens after the program hits the break. So array[index] = x; didn't get executed.

On the while loop since there's no break, the loop continues, so the statements array[index] = x; and index++; got executed.

That's why you got different results. If you don't want the statements

array[index] = x;
index++;

To be executed you can simply make your if statement a if/else statement as above.

edited Dec 9, 2015 at 0:03

answered Dec 8, 2015 at 23:57

gooeyn

908 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Elliott Frisch · Accepted Answer · 2015-12-08 23:55:12Z

1

Change

if (x < 0) 
{
    count--;
}
array[index] = x;
index++;

to something like

if (x < 0) 
{
    count--;
} 
else 
{
    array[index] = x;
    index++;
}

answered Dec 8, 2015 at 23:55

Elliott Frisch

202k20 gold badges166 silver badges265 bronze badges

Comments

Andreas Vogl · Accepted Answer · 2015-12-08 23:55:54Z

1

If you want to avoid break, changing the for loop into a while loop doesn't help in any way.

How about this solution:

boolean exitLoop = false;
for (int index = 0; index < array.length && !exitLoop; index++)
    {
        System.out.print("Sample " + (index+1) + ": ");
        double x = scan.nextDouble();
        count++;
        if (x < 0) 
        {
            count--;
            exitLoop = true;
        }
        else {
            array[index] = x;
        }
    }

answered Dec 8, 2015 at 23:55

Andreas Vogl

1,8731 gold badge16 silver badges19 bronze badges

Collectives™ on Stack Overflow

Converting for loop to while loop in Java

3 Answers 3

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related