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Thread: HELP ME HOW TO DECREMENT THIS PLS

  1. #1
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    Default HELP ME HOW TO DECREMENT THIS PLS

    int [ ] arr = new int[ 4 ]
    for(int i = 0; i < arr.length; i++)
    arr[ i ] = i + 1
    System.out.println(arr[ i ]++)


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    What is your question? What is the problem? What does this code do? What is it supposed to do? Please see the link in my signature on asking questions the smart way.

    You decrement exactly how you increment, only with subtraction instead of addition.

    Also, I recommend you surround the body of your for loop with curly brackets { }, otherwise you're only executing the single line following the loop.
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    i did it on purpose..when i use -- it says outofbounds

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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    it says outofbounds
    That JVM is fussy about you're using indexes that go past the end of an array.
    Check your code to be sure you do not allow that to happen.

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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    Quote Originally Posted by jeremanalaotao View Post
    i did it on purpose..when i use -- it says outofbounds
    Okay, and what did you expect to happen?
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    int [ ] arr = new int[ 10 ];

    for(int i =8; i < arr.length; i--){
    arr[ i ] = i - 1;
    System.out.println(arr[ i ]);


    this is my code for decrement..but it says "Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1"

  7. #7
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    Quote Originally Posted by jeremanalaotao View Post
    int [ ] arr = new int[ 10 ];

    for(int i =8; i < arr.length; i--){
    arr[ i ] = i - 1;
    System.out.println(arr[ i ]);


    this is my code for decrement..but it says "Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1"
    When do you expect that loop to exit?
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    i want to exit that at 0 hehe

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    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    Quote Originally Posted by jeremanalaotao View Post
    i want to exit that at 0 hehe
    So now do you have it figured out?
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    not yet...zzzzzzz

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    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    Well, look at your exit condition- it's the second part of the for loop declaration (i < arr.length). The for loop exits when that evaluates to false. But if you're starting at length-1 and only decrementing, that will never be false.
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    Default Re: HELP ME HOW TO DECREMENT THIS PLS

    You must read the syntax of the for loop. Kevin has provided you with the best answer. He told you your condition.
    So for loop's syntax is actually
    Syntax:
    for(initialization;condition;iteration){
    //body of loop;
    }
    And you have successfully done your initialization and iteration (decrement). You have problem in your condition.
    You said you want for loop to run till 0.
    You are starting from 8. Your array size is 10. You are actually starting from 8 and you are limiting your loop to go till size of array (10).
    First time your loop starts, value is 8 that is less than 10, true. Works fine. You decrement one and value becomes 7.... and 6,5,4,3,2,1,0,-1 and so on....
    You will never have array index as -1. And this is the problem. Index out of bounds.
    Now think and try to solve.
    Luck

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