Swap two arrays without completely allocating a third (C++)

Question

I have two arrays of type Region , both of size 1000, and at every iteration of a loop I want to swap the two of them (by swapping their memory addresses). I was hoping this would work:

        Region *swap = (Region*)myRegions;
        myRegionsLast = myRegions;
        myRegions = (Region[1000])swap;

Line one seems fine. The second and third lines are invalid assignments, as you apparently can't re-assign that type. The third line is also invalid because you can't cast to the type (Region [1000]) . Obviously I don't want to allocate whole new Region[1000] if I can help it. Can someone help me accomplish what I want?

Answer 1

This happens because you cannot assign a whole array at once. You can assign a pointer, however:

Region reg1[1000], reg2[1000];
Region *myRegionsLast = reg1;
Region *myRegions = reg2;

Now your swap routine is going to work without further modifications.

You could also swap arrays one element at a time, but it is going to involve a lot more data copying.

Answer 2

How about creating just a variable of the content of Region type and iterating through it...

for(int i=0; i<1000; i++)
{
    tempRegionTypeVariable = myRegionsLast[i];
    myRegionsLast[i] = myRegions[i];
    myRegions[i] = tempRegionTypeVariable;
}

Hope this helps.. Here "tempRegionTypeVariable" is just a temporary variable or an Object. Not an Array..

Answer 3

A couple other valid answers were posted in the comments:

1. Use std::swap() / std::array::swap
2. Make them dynamically allocated arrays instead of static