Hopefully, this is a tractable problem...

This is a discussion on Hopefully, this is a tractable problem... within the C Programming forums, part of the General Programming Boards category; I have an array of pointers to N arrays (see my earlier post). I happy with the assignment of these ...

  1. #1
    Not bad at Crack Attack!
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    Hopefully, this is a tractable problem...

    I have an array of pointers to N arrays (see my earlier post). I happy with the assignment of these things and I can access the elements of these arrays with ease. Fantastic.

    However, I am now required to modify these arrays, specifically I need to add elements to these arrays. This is done in the form of a function which has an integer, "i" say, passed to it. A random number is generated, call it x for example.

    Code:
    int *array[]={N0, .... , Ni, Nj, Nk, ... , NN};
    
    void add_to_array(int i)
    {
    int x;
    x=rand()
    
    /*How do I add x to array Ni???*/
    return;
    }
    If it helps I also have an array of length N where the i^th element comprises the number of elements in the i^th array. (If I refer to this particular array again, I will call it "noe"...)

    My current approach is to copy the existing array (array[i] using the code above), free it and then increase noe[i] by 1, then malloc a new Ni, fill it from the copy and stick x in at the end. However, I need to do this multiple times! I get a gut feeling that this will cause a problem... Using the most simplistic approach and calling the new array "new" then surely I cannot call the function more than once for fearing of really confusing things??!?



    I hope this is reasonably clear. I would rather not post the code I am actually working on or give too much of the context away because I am not looking to have code written for me... merely an approach suggested to help me on my way.

    Matt

  2. #2
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    I am intruiged by "realloc". I've not come across it (I've only been C'ing - slowly - for approx 6 months) - just a few words to describe it or a link to a description maybe?

    Thanks for the help, I will have a look but it looks as though your suggestions will work - but I have to translate it all to my context of course...

  3. #3
    Just Lurking Dave_Sinkula's Avatar
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    >a link to a description maybe?

    http://www.rt.com/man/realloc.3.html
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  4. #4
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    Originally posted by Matt13
    I am intruiged by "realloc". I've not come across it (I've only been C'ing - slowly - for approx 6 months) - just a few words to describe it or a link to a description maybe?

    Thanks for the help, I will have a look but it looks as though your suggestions will work - but I have to translate it all to my context of course...
    Thanks a lot, I have that bookmarked. I was familiar with malloc and calloc - discovering there is a realloc has made my day!

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