memcpy question

This is a discussion on memcpy question within the C Programming forums, part of the General Programming Boards category; Say we have 2 arrays of size ten, the second array as 6 ints in it. If i do a ...

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    memcpy question

    Say we have 2 arrays of size ten, the second array as 6 ints in it.
    If i do a memcpy(array1, array2 10);
    Will i get rubbish in the after the 6 spot in the array1 or will memcpy set them to null;

    ie what be the valueof array1[7] - [9]

    Is memset more safer before the memcpy on the array?
    Thanks
    Last edited by newbie30; 12-09-2009 at 05:29 AM.

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    C++まいる!Cをこわせ! Elysia's Avatar
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    memcpy will only copy memory from one place to another. It will not in any way manipulate anything by setting it to 0 or null. So the answer to that question is: if there is rubbish in the array you copy, then yes, the destination will have it too.

    The second questions depends on what you use it for. For example, do you somehow depend on some elements that are not in use being 0? If so, then yes. Otherwise, it's probably a no.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
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    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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    Quote Originally Posted by newbie30 View Post
    Say we have 2 arrays of size ten, the second array as 6 ints in it.
    If i do a memcpy(array1, array2 10);
    That wont work, the size parameter is number of bytes. If your array consists of ints, 10 bytes wont cover the whole array.

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