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C++ beginner question

This is a discussion on C++ beginner question within the C++ Programming forums, part of the General Programming Boards category; Hi, I am a beginner. I'm working from a book called "The complete idiot's guide to c++". And I feel ...

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    Question C++ beginner question

    Hi,

    I am a beginner. I'm working from a book called "The complete idiot's guide to c++". And I feel like an idiot, because I can't figure out the following.

    The question in the book is from the Polymorphism chapter 22. Specifically, from a STACK to a LIST.
    The part I am struggling with is:
    I need to ask the user for them to select an element (not an offset) from an array & then remove that element from the array. Then the higher-placed elements will be shuffled down one place to fill the empty element. The elements below will remain unchanged. I think I have the part where I ask the user to select the element, but I'm struggling to figure out how to then remove that element & shuffle the higher-placed elements down one & leave the other elements untouched.
    Can someone please help?

    I hope I provided enough details!
    Margie

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    So, do you have a stack, an array, or a list? You shouldn't have a stack, because you can't access elements in the middle of a stack. Deleting from an array involves moving all the other elements down one spot (so you've vacated spot 8; now you have to put element 9 in spot 8, element 10 in spot 9, element 11 in spot 10) etc. Removing from a list just involves moving some pointers around.

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    I have a LIST. I started like this, but I'm just struggling so badly with the removing of the element from the LIST & then shuffling!

    for (index = 1; index < back; index++)
    {
    cout << "Enter the LIST element you wish to view ";
    cin >> data[index];

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    Sorry I made a mistake there, it should say, "Enter the list element you wish to remove".

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    and the Hat of Guessing tabstop's Avatar
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    If you have a list, then there is no shuffling that is required -- you'll just set the pointer of n-1 to point to n+1 instead, and that takes element n right out of your loop.

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    If you are talking about shuffling the results down, you do not have a list, you have an array. If you are using C++ you should actually use the list container in the STL. Often times when beginning programming it is difficult to get the answers you want because of misusing words to describe problems. May I suggest you post a little more code to demonstrate what you are doing and where in your code you are stumped. Specifically, where you define your 'list'.

    Also here is a link to some good book recommendations. As a general rule, stay away from those 'for dummies' books. In my experience they were written by dummies.
    Quote Originally Posted by anduril462 View Post
    Now, please, for the love of all things good and holy, think about what you're doing! Don't just run around willy-nilly, coding like a drunk two-year-old....
    Quote Originally Posted by quzah View Post
    ..... Just don't be surprised when I say you aren't using standard C anymore, and as such,are off in your own little universe that I will completely disregard.
    Warning: Some or all of my posted code may be non-standard and as such should not be used and in no case looked at.

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    Algorithm Dissector iMalc's Avatar
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    Arrays start at zero, not one.
    You need to start by thinking about the steps involved in removing an item.

    If you had a row of 5 jellybeans and you wanted to remove the middle jellybean, and get rid of the gap, what steps are involved?
    Note that you are only ever allowed to touch one jellybean at a time and jellybeans are not allowed to touch each other.
    You start by eating the middle one, and then what...?
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    C++ Witch laserlight's Avatar
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    Quote Originally Posted by AndrewHunter
    If you are talking about shuffling the results down, you do not have a list, you have an array.
    Actually, it sounds like margiesam has a list that is implemented with an array rather than a linked list.

    Quote Originally Posted by AndrewHunter
    If you are using C++ you should actually use the list container in the STL. Often times when beginning programming it is difficult to get the answers you want because of misusing words to describe problems.
    You, tabstop and the C++ standard misused "list" to always mean "linked list"
    AndrewHunter likes this.
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