CODEWITHSUNDEEP
javafile
user2932587
user2932587

Reputation:

Ending a Program When a Negative Number is Read From a File

I'm working on a program that is supposed to read numbers (double) in from a file and perform some calculations on them (creating octagon objects). However, we are supposed to end the program when a negative number is read in, and I'm not sure how to do this?

The file that is being used looks like this:

5.0
7.5
3.26
0.0
-1.0

I am using a while loop to read in the file and assign the values to variables, so would I just need to add something to my while loop to end if the number is negative? Something like:

while(fin.hasNext()) {
    double side = fin.nextDouble();
        if(side < 0) 
            //do whatever I need to do to end the program
 }

Or am I totally wrong in that thinking?

Thanks in advance for any input.

Upvotes: 1

Views: 607

Answers (2)

gyroninja
gyroninja

Reputation: 111

It would be as simple as doing

while(fin.nextDouble()) {

    double d = fin.nextDouble();

    if (d < 0) {

        break;
    }

    ...
}

Another approach to doing this would be doing

double d;

while(fin.hasNextDouble() && (d = fin.nextDouble()) >= 0) {

    ...
}

Upvotes: 1

mleyfman
mleyfman

Reputation: 635

This doesn't quite work, because fin.hasNext() only returns whether or not the next line is EOF (aka there is no more text), not the contents themselves. You will need to check for a negative value inside the loop. This is done by calling nextDouble() and comparing it with 0, and then breaking if it isn't positive. All of this is assuming that you are using Java's Scanner class.

The code would be:

while (fin.hasNextDouble()) {
    double num = fin.nextDouble();

    if (num < 0.0) break;

    // do your stuff

Upvotes: 1

Related Questions