Can you make arrays equal to each other
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Thread: Can you make arrays equal to each other

  1. #1
    Join Date
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    Question Can you make arrays equal to each other

    Is there a way to make the elements of an array equal to the elements of another array?
    I know that you can do it in a loop but I'm looking for something like a shortcut.

  2. #2
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    Re: Can you make arrays equal to each other

    Well...depending on the type of the array. In case you are using STL containers then take a look at the following algorithms:
    • copy (for unsorted ranges)
    • merge (for sorted ranges)
    • set_union (for sorted ranges - elements in both source ranges end up only once in destination range)
    • set_intersection (for sorted ranges - only elements that are in both source ranges)


    Edit: Okay....I guess, I actually misunderstood the question...if you want to make one array equal to the other, then the 'copy' algorithm is actually the one you are looking for (which can even be used with POD types). The other three are actually used for merging. Sorry for not paying attention in the first place and thanks to Lindley for giving me the wake up.
    Last edited by Andreas Masur; January 10th, 2009 at 11:45 PM. Reason: Brain cells were already sleeping....
    Ciao, Andreas

    "Software is like sex, it's better when it's free." - Linus Torvalds


    Article(s): Allocators (STL) Function Objects (STL)

  3. #3
    Lindley is offline Elite Member Power Poster
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    Re: Can you make arrays equal to each other

    In the event the array is of a plain-old-data type, you can always use memcpy(). std::copy() should be preferred, though, since it (probably) reduces to memcpy() in the POD case, while also correctly handling non-POD types.

  4. #4
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    Re: Can you make arrays equal to each other

    Quote Originally Posted by E-man96 View Post
    Is there a way to make the elements of an array equal to the elements of another array?
    I know that you can do it in a loop but I'm looking for something like a shortcut.
    Code:
    #include <algorithm>
    
    SomeType array1[10];
    SomeType array2[10];
    
    //...
    std::copy(array1, array1 + 10, array2);  // set array2 equal to array1
    Regards,

    Paul McKenzie

  5. #5
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    Re: Can you make arrays equal to each other

    Quote Originally Posted by E-man96 View Post
    Is there a way to make the elements of an array equal to the elements of another array?
    I know that you can do it in a loop but I'm looking for something like a shortcut.
    There's no built-in C++ language feature available (like field operations or so), so you must copy explicitly in one way or another.

    Note that if you're doing extensive copying of large amounts of data, then you could consider using a fine-grain parallel library, like Intel TBB, to make it faster on multi-core processors.
    Last edited by _uj; January 11th, 2009 at 01:25 AM.

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