Duplicating arrays

This is a discussion on Duplicating arrays within the C Programming forums, part of the General Programming Boards category; Hi!! This is my first post on the forum, because I've been having trouble trying to do this. How can ...

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    Duplicating arrays

    Hi!!

    This is my first post on the forum, because I've been having trouble trying to do this. How can I from an array that's [i][j] duplicate it's column and line values to a [2*i][2*j]?
    For example : [2,4];[5,6] to [2,2,4,4];[2,2,4,4];[5,5,6,6];[5,5,6,6]
    And how can I do the inverse, remove alternatively column and line.
    For example: [1,2,3,4];[5,6,7,8];[9,10,11,12];[13,14,15,16] to [1,3];[9,11]


    Thanks!

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    Just do newArray[i][j] = oldArray[i/2][j/2] for each i, j.

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    Quote Originally Posted by TomasRiker View Post
    Just do newArray[i][j] = oldArray[i/2][j/2] for each i, j.
    That covers the second case.
    For the first case you want to assign each value to the four locations:
    [i*2][j*2]
    [i*2+1][j*2]
    [i*2][j*2+1]
    [i*2+1][j*2+1]
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    Quote Originally Posted by TomasRiker View Post
    Just do newArray[i][j] = oldArray[i/2][j/2] for each i, j.
    First case is working, as for the second case tried and it doesn't work and I can't understand why it puts the new array all with 1's plus it alters the first row of the original one.

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    Algorithm Dissector iMalc's Avatar
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    Quote Originally Posted by interneft View Post
    First case is working, as for the second case tried and it doesn't work and I can't understand why it puts the new array all with 1's plus it alters the first row of the original one.
    Actually, my mistake, the other guy's suggestion was also for the first case, and is probably the simpler way of doing it.
    For the second case you can just turn the /2 into *2.
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