numbers problem in code

Question

I'm having some problem with my code. It works fine when I compile it until I get to the point when the numbers divide. I'm not getting numbers with decimal, only zero. As you can see, I already changed the last variables to double but it didn't have any meaningful result.

What must I do to change this?

        int[] arr = new int[2];
        System.out.println("enter two numbers: ");
        arr[0] = sc.nextInt();
        arr[1] = sc.nextInt();

        int summa = arr[0]+arr[1];

        System.out.println("What's "+arr[0]+" + "+arr[1]+" ?");
        int vad = sc.nextInt();

        if (summa == vad)
            System.out.println("Correct!");
        else
            System.out.println("Wrong - The right answer is "+summa);


        int summa2 = arr[0]-arr[1];
        System.out.println("What's "+arr[0]+" - "+arr[1]+" ?");
        int vad2 = sc.nextInt();

        if (summa2 == vad2)
            System.out.println("Correct!");
        else
            System.out.println("Wrong - The right answer is: "+summa2);


        int summa3 = arr[0]*arr[1];
        System.out.println("What's "+arr[0]+" * "+arr[1]+" ?");
        int vad3 = sc.nextInt();

        if (summa3 == vad3)
            System.out.println("Correct!");
        else
            System.out.println("Wrong - The right answer is "+summa3);


        double summa4 = arr[0]/arr[1];
        System.out.println("What's "+arr[0]+" / "+arr[1]+" ?");
        double vad4 = sc.nextInt();

        if (summa4 == vad4)
            System.out.println("Correct!");
        else
            System.out.println("Wrong - The right answer is "+summa4);



}

}

Jigar Joshi · Accepted Answer · 2010-12-20 11:23:56Z

4

1 you are reading int it should be double .
2 You need to cast to double check code below

    double summa4 = ((double)arr[0])/arr[1];
    System.out.println("What's "+arr[0]+" / "+arr[1]+" ?");
    double vad4 = sc.nextDouble();

    if (summa4 == vad4)
        System.out.println("Correct!");
    else
        System.out.println("Wrong - The right answer is "+summa4);

answered Dec 20, 2010 at 11:23

Jigar Joshi

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1 Comment

rsp Over a year ago

and 3) compare doubles using a range like (summa4 <= vad4 + 0.01 && summa4 >= vad4 - 0.01) testing doubles for equality is a problem because of floating point artifacts.

Shamim Hafiz - MSFT · Accepted Answer · 2010-12-20 11:24:20Z

2

Although summa4 variable is of type double, but it's calculation is done in integer division. Therefore, the result would not have any decimal place.

For example, 5/2 = 2 and not 2.5 if both 5 and 2 are integers or values stored in int type variable.

change:

double summa4 = arr[0]/arr[1];

to

double summa4 = 1.0*arr[0]/arr[1];

answered Dec 20, 2010 at 11:24

Shamim Hafiz - MSFT

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