Thread: Partial vector swapping.

  1. #1
    Registered User
    Join Date
    Aug 2006

    Partial vector swapping.

    I have two vectors of ints. I need to cut each of them at some arbitrary point and swap the last half of each. So, if I have:
    a = {1, 2, 3, 4, 5, 6}
    b = {7, 8, 9, 10, 11, 12}
    and I swap at the middle, the resulting vectors would be:
    a = {1, 2, 3, 10, 11, 12}
    b = {7, 8, 9, 4, 5, 6}
    Now, I could iterate through them and perform the swap to a temporary vector, but I was wondering if there was a function in the STL that would do this for me?

  2. #2
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    There is the std::swap_ranges() standard generic algorithm that you can use, e.g.,

    Assuming that the vectors are of equal length:
    const std::vector<int>::size_type mid = vec1.size() / 2;
    std::swap_ranges(vec1.begin() + mid, vec1.end(), vec2.begin() + mid);
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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