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Thread: Please see multiple questions I got wrong on an exam, what I did wrong?

  1. #1
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    Default Please see multiple questions I got wrong on an exam, what I did wrong?

    Here is a list of what I had gotten wrong on an exam:

    boolan a = false, b = true, c = true, d = false, e = true;

    1. System.out.println a != c;

    I had converted it to a==c, and had answered FALSE. I'm checking the answer again -- and since a = false, c = true; the result of a == c would be FALSE. FALSE was my answer.

    But I got the answer wrong, did I read too much into it and convert the not equals into ==, when I should've left it alone, and resulting in a != c being TRUE. because that would be true, a(false) doesn't equal c(true.

    2. This was a question that asked for showing the EXACT output that will be created by execution of the following program.

    package javaapplication1;
     
     
    public class JavaApplication1
    {
     
        public static void main (String[] args) 
        {
            int manny = 40, moe = 23, jack = 26;
            System.out.printf ("%3d%3d%3d\n", manny, moe, ++jack);
                if (manny > moe)
                    if (moe > jack) {
                            moe = 40;
                            System.out.printf ("%3d%3d\n", ++jack, moe--);
                        }
                    else
                            manny-=manny;
                else
                    if(moe > jack)
                            jack = 50;
                    else
                        System.out.printf ("%3d%3d\n", ++jack, moe--);
              System.out.printf("%3d%3d%3d\n", manny, moe, ++jack);
               if (manny > moe)
                   if (moe > jack)  {
                            moe = 31;
                            System.out.printf("%3d%3d\n", ++jack, moe--);
                   }
               else
                            manny -= manny;
           else
               if(moe > jack)
                       jack = 50;
               else
                   System.out.printf ("%3d%3d\n", ++jack, moe--);
           System.out.printf("%3d%3d%3d\n", manny, moe, ++jack);
        }
    }

    Here is how I tracked my variables, I would cross them out as I read through the program and the most bottom one would be the newest value
    manny moe jack
    40 23 26
    0 22 27
    28
    29

    My output looked like this(everything had to be exact, spacing is indicated by the underscore _ )
    OUTPUT
    _40_23_27
    _28_23
    __0_22_29


    Please help me learn what I did wrong.


  2. #2
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    Default Re: Please see multiple questions I got wrong on an exam, what I did wrong?

    1. You're confusing me with your thought process, so I'm going to ignore it for a bit. This is what I see:

    Given:
    a = false, c = true

    The statement:
    a != c (say, "a does not equal c")

    is TRUE, because (substitute from the givens):
    false != true (say, "false does not equal true")

    I don't have time now for #2, but I'll look at it later.

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    Default Re: Please see multiple questions I got wrong on an exam, what I did wrong?

    _40_23_27
    __0_23_28
    _29 23
    __0_22_30

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    Default Re: Please see multiple questions I got wrong on an exam, what I did wrong?

    Did you get number 2 right or wrong?

    If you got it wrong, a great way to figure out why is to actually type that program up and compile and run it. Add some print statements so you know the value of each variable on each line.
    Useful links: How to Ask Questions the Smart Way | Use Code Tags | Java Tutorials
    Static Void Games - Play indie games, learn from game tutorials and source code, upload your own games!

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    Default Re: Please see multiple questions I got wrong on an exam, what I did wrong?

    Quote Originally Posted by ggx7 View Post
    Please help me learn what I did wrong.
    ggx7
    It looks like you are evaluating statements that are made within an "else" that shouldn't be evaluated.
    Eg
    The first if statement
    if (manny > moe)

    is true, so you would never evaluate the "else" statement for that, even though by the time you get to that 'else' line, the original if statement would now be evaluated as false (because you aren't evaluating that if statement again, it was true when it was evaluated and that's all that matters, so skip the else).

    Follow Kevin's advice and just compile this code and see what you get...

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